chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chrome.browser.tab;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.Rect;
import android.net.Uri;
import android.os.Bundle;
import android.provider.Browser;
import android.support.annotation.IntDef;
import android.support.annotation.Nullable;
import android.text.TextUtils;
import android.view.ContextThemeWrapper;
import android.view.View;
import android.view.View.OnAttachStateChangeListener;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;

import org.chromium.base.ApplicationStatus;
import org.chromium.base.ContextUtils;
import org.chromium.base.Log;
import org.chromium.base.ObserverList;
import org.chromium.base.ObserverList.RewindableIterator;
import org.chromium.base.TraceEvent;
import org.chromium.base.UserDataHost;
import org.chromium.base.VisibleForTesting;
import org.chromium.base.annotations.CalledByNative;
import org.chromium.chrome.R;
import org.chromium.chrome.browser.AppHooks;
import org.chromium.chrome.browser.ChromeActionModeCallback;
import org.chromium.chrome.browser.ChromeActivity;
import org.chromium.chrome.browser.ChromeFeatureList;
import org.chromium.chrome.browser.ChromeVersionInfo;
import org.chromium.chrome.browser.IntentHandler;
import org.chromium.chrome.browser.IntentHandler.TabOpenType;
import org.chromium.chrome.browser.SwipeRefreshHandler;
import org.chromium.chrome.browser.UrlConstants;
import org.chromium.chrome.browser.WarmupManager;
import org.chromium.chrome.browser.WebContentsFactory;
import org.chromium.chrome.browser.banners.AppBannerManager;
import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
import org.chromium.chrome.browser.content.ContentUtils;
import org.chromium.chrome.browser.contextmenu.ContextMenuPopulator;
import org.chromium.chrome.browser.contextualsearch.ContextualSearchTabHelper;
import org.chromium.chrome.browser.crypto.CipherFactory;
import org.chromium.chrome.browser.customtabs.CustomTabActivity;
import org.chromium.chrome.browser.document.ChromeLauncherActivity;
import org.chromium.chrome.browser.fullscreen.FullscreenManager;
import org.chromium.chrome.browser.fullscreen.FullscreenOptions;
import org.chromium.chrome.browser.infobar.InfoBarContainer;
import org.chromium.chrome.browser.media.ui.MediaSessionTabHelper;
import org.chromium.chrome.browser.native_page.FrozenNativePage;
import org.chromium.chrome.browser.native_page.NativePage;
import org.chromium.chrome.browser.native_page.NativePageAssassin;
import org.chromium.chrome.browser.native_page.NativePageFactory;
import org.chromium.chrome.browser.offlinepages.OfflinePageUtils;
import org.chromium.chrome.browser.policy.PolicyAuditor;
import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
import org.chromium.chrome.browser.previews.PreviewsAndroidBridge;
import org.chromium.chrome.browser.profiles.Profile;
import org.chromium.chrome.browser.rlz.RevenueStats;
import org.chromium.chrome.browser.ssl.SecurityStateModel;
import org.chromium.chrome.browser.tab.TabState.WebContentsState;
import org.chromium.chrome.browser.tab.TabUma.TabCreationState;
import org.chromium.chrome.browser.tabmodel.AsyncTabParamsManager;
import org.chromium.chrome.browser.tabmodel.TabLaunchType;
import org.chromium.chrome.browser.tabmodel.TabModel;
import org.chromium.chrome.browser.tabmodel.TabModelSelector;
import org.chromium.chrome.browser.tabmodel.TabReparentingParams;
import org.chromium.chrome.browser.tabmodel.TabSelectionType;
import org.chromium.chrome.browser.vr.VrModuleProvider;
import org.chromium.components.dom_distiller.core.DomDistillerUrlUtils;
import org.chromium.components.embedder_support.view.ContentView;
import org.chromium.components.navigation_interception.InterceptNavigationDelegate;
import org.chromium.components.security_state.ConnectionSecurityLevel;
import org.chromium.content_public.browser.ChildProcessImportance;
import org.chromium.content_public.browser.GestureListenerManager;
import org.chromium.content_public.browser.ImeAdapter;
import org.chromium.content_public.browser.ImeEventObserver;
import org.chromium.content_public.browser.LoadUrlParams;
import org.chromium.content_public.browser.SelectionPopupController;
import org.chromium.content_public.browser.WebContents;
import org.chromium.content_public.browser.WebContentsAccessibility;
import org.chromium.content_public.common.BrowserControlsState;
import org.chromium.content_public.common.Referrer;
import org.chromium.content_public.common.ResourceRequestBody;
import org.chromium.ui.base.LocalizationUtils;
import org.chromium.ui.base.PageTransition;
import org.chromium.ui.base.WindowAndroid;
import org.chromium.ui.mojom.WindowOpenDisposition;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.nio.ByteBuffer;

/**
 * The basic Java representation of a tab.  Contains and manages a {@link ContentView}.
 * This class is not intended to be extended.
 */
public class Tab
        implements ViewGroup.OnHierarchyChangeListener, View.OnSystemUiVisibilityChangeListener {
    public static final int INVALID_TAB_ID = -1;

    /** Return value from {@link #getBookmarkId()} if this tab is not bookmarked. */
    public static final long INVALID_BOOKMARK_ID = -1;

    private static final long INVALID_TIMESTAMP = -1;

    /** Used for logging. */
    private static final String TAG = "Tab";

    private static final String PRODUCT_VERSION = ChromeVersionInfo.getProductVersion();

    /**
     * A list of the various ways tabs can be hidden.
     */
    @IntDef({TabHidingType.CHANGED_TABS, TabHidingType.ACTIVITY_HIDDEN, TabHidingType.REPARENTED})
    @Retention(RetentionPolicy.SOURCE)
    public @interface TabHidingType {
        /** A tab was hidden due to other tab getting foreground. */
        int CHANGED_TABS = 0;

        /** A tab was hidden together with an activity. */
        int ACTIVITY_HIDDEN = 1;

        /** A tab was hidden while being reparented to a new activity. */
        int REPARENTED = 2;
    }

    private long mNativeTabAndroid;

    /** Unique id of this tab (within its container). */
    private final int mId;

    /** Whether or not this tab is an incognito tab. */
    private final boolean mIncognito;

    /**
     * An Application {@link Context}.  Unlike {@link #mActivity}, this is the only one that is
     * publicly exposed to help prevent leaking the {@link Activity}.
     */
    private final Context mThemedApplicationContext;

    /** Gives {@link Tab} a way to interact with the Android window. */
    private WindowAndroid mWindowAndroid;

    /** Whether or not this {@link Tab} is initialized and should be interacted with. */
    private boolean mIsInitialized;

    /** The current native page (e.g. chrome-native://newtab), or {@code null} if there is none. */
    private NativePage mNativePage;

    /** {@link WebContents} showing the current page, or {@code null} if the tab is frozen. */
    private WebContents mWebContents;

    /** The parent view of the ContentView and the InfoBarContainer. */
    private ViewGroup mContentView;

    /** A list of Tab observers.  These are used to broadcast Tab events to listeners. */
    private final ObserverList<TabObserver> mObservers = new ObserverList<>();

    // Content layer Delegates
    private TabWebContentsDelegateAndroid mWebContentsDelegate;

    /**
     * If this tab was opened from another tab, store the id of the tab that
     * caused it to be opened so that we can activate it when this tab gets
     * closed.
     */
    private int mParentId = INVALID_TAB_ID;

    /**
     * By default, this id inherits from the tab that caused it to be opened, or it equals to tab
     * id. This is used to restore the relationship that defined by {@link TabModelFilter} between
     * this tab and other tabs. This id can be re-set whenever is needed.
     */
    private int mRootId;

    /**
     * If this tab was opened from another tab in another Activity, this is the Intent that can be
     * fired to bring the parent Activity back.
     * TODO(dfalcantara): Remove this mechanism when we have a global TabManager.
     */
    private Intent mParentIntent;

    /**
     * Whether the tab should be grouped with its parent tab.
     */
    private boolean mGroupedWithParent = true;

    private boolean mIsClosing;
    private boolean mIsShowingErrorPage;
    private boolean mIsShowingTabModalDialog;

    private Bitmap mFavicon;
    private int mFaviconWidth;
    private int mFaviconHeight;
    private String mFaviconUrl;

    /**
     * The size in pixels at which favicons will be drawn. Ideally mFavicon will have this size to
     * avoid scaling artifacts.
     */
    private int mIdealFaviconSize;

    /** Whether or not the TabState has changed. */
    private boolean mIsTabStateDirty = true;

    /**
     * Saves how this tab was launched (from a link, external app, etc) so that
     * we can determine the different circumstances in which it should be
     * closed. For example, a tab opened from an external app should be closed
     * when the back stack is empty and the user uses the back hardware key. A
     * standard tab however should be kept open and the entire activity should
     * be moved to the background.
     */
    private final @Nullable @TabLaunchType Integer mLaunchType;

    /**
     * Saves how this tab was initially launched so that we can record metrics on how the
     * tab was created. This is different than {@code mLaunchType}, since {@code mLaunchType} will
     * be overridden to "FROM_RESTORE" during tab restoration.
     */
    private @Nullable @TabLaunchType Integer mLaunchTypeAtCreation;

    /**
     * Navigation state of the WebContents as returned by nativeGetContentsStateAsByteBuffer(),
     * stored to be inflated on demand using unfreezeContents(). If this is not null, there is no
     * WebContents around. Upon tab switch WebContents will be unfrozen and the variable will be set
     * to null.
     */
    private WebContentsState mFrozenContentsState;

    /**
     * URL load to be performed lazily when the Tab is next shown.
     */
    private LoadUrlParams mPendingLoadParams;

    /**
     * URL of the page currently loading. Used as a fall-back in case tab restore fails.
     */
    private String mUrl;

    /**
     * The external application that this Tab is associated with (null if not associated with any
     * app). Allows reusing of tabs opened from the same application.
     */
    private String mAppAssociatedWith;

    /**
     * Keeps track of whether the Tab should be kept in the TabModel after the user hits "back".
     * Used by Document mode to keep track of whether we want to remove the tab when user hits back.
     */
    private boolean mShouldPreserve;

    /**
     * True while a page load is in progress.
     */
    private boolean mIsLoading;

    /**
     * True while a restore page load is in progress.
     */
    private boolean mIsBeingRestored;

    /**
     * Whether or not the Tab is currently visible to the user.
     */
    private boolean mIsHidden = true;

    /**
     * Importance of the WebContents currently attached to this tab. Note the key difference from
     * |mIsHidden| is that a tab is hidden when the application is hidden, but the importance is
     * not affected by this signal.
     */
    private @ChildProcessImportance int mImportance = ChildProcessImportance.NORMAL;

    /** Whether the renderer is currently unresponsive. */
    private boolean mIsRendererUnresponsive;

    /**
     * The last time this tab was shown or the time of its initialization if it wasn't yet shown.
     */
    private long mTimestampMillis = INVALID_TIMESTAMP;

    /**
     * Title of the ContentViews webpage.Always update mTitle through updateTitle() so that it also
     * updates mIsTitleDirectionRtl correctly.
     */
    private String mTitle;

    /**
     * Indicates if mTitle should be displayed from right to left.
     */
    private boolean mIsTitleDirectionRtl;

    /**
     * The mInterceptNavigationDelegate will be consulted for top-level frame navigations. This
     * allows presenting the intent picker to the user so that a native Android application can be
     * used if available.
     */
    private InterceptNavigationDelegateImpl mInterceptNavigationDelegate;

    /**
     * Whether didCommitProvisionalLoadForFrame() hasn't yet been called for the current native page
     * (page A). To decrease latency, we show native pages in both loadUrl() and
     * didCommitProvisionalLoadForFrame(). However, we mustn't show a new native page (page B) in
     * loadUrl() if the current native page hasn't yet been committed. Otherwise, we'll show each
     * page twice (A, B, A, B): the first two times in loadUrl(), the second two times in
     * didCommitProvisionalLoadForFrame().
     */
    private boolean mIsNativePageCommitPending;

    private FullscreenManager mFullscreenManager;

    /**
     * Indicates whether this tab is detached from any activity and its corresponding
     * {@link WindowAndroid}.
     */
    private boolean mIsDetached;

    /** Whether or not the tab closing the tab can send the user back to the app that opened it. */
    private boolean mIsAllowedToReturnToExternalApp;

    private int mTopControlsHeight;
    private int mBottomControlsHeight;
    private boolean mControlsResizeView;

    /**
     * The publisher URL for pages hosted on a trusted CDN, or null otherwise.
     */
    private @Nullable String mTrustedCdnPublisherUrl;

    /** The current browser controls constraints. -1 if not set. */
    private @BrowserControlsState int mBrowserConstrolsConstraints = -1;

    // TODO(dtrainor): Port more methods to the observer.
    private final TabObserver mTabObserver = new EmptyTabObserver() {
        @Override
        public void onSSLStateUpdated(Tab tab) {
            PolicyAuditor auditor = AppHooks.get().getPolicyAuditor();
            auditor.notifyCertificateFailure(
                    PolicyAuditor.nativeGetCertificateFailure(getWebContents()),
                    getApplicationContext());
        }

        @Override
        public void onWebContentsSwapped(Tab tab, boolean didStartLoad, boolean didFinishLoad) {
            if (!didStartLoad) return;

            String url = tab.getUrl();
            // Simulate the PAGE_LOAD_STARTED notification that we did not get.
            didStartPageLoad(url);

            if (didFinishLoad) {
                // Simulate the PAGE_LOAD_FINISHED notification that we did not get.
                didFinishPageLoad(url);
            }
        }
    };

    private final TabObserver mFullscreenHandler = new TabFullscreenHandler();

    private TabDelegateFactory mDelegateFactory;

    private BrowserControlsVisibilityDelegate mBrowserControlsVisibilityDelegate;

    /** Listens for views related to the tab to be attached or detached. */
    private OnAttachStateChangeListener mAttachStateChangeListener;

    /** Whether the tab can currently be interacted with. */
    private boolean mInteractableState;

    /** Whether or not the tab's active view is attached to the window. */
    private boolean mIsViewAttachedToWindow;

    private final UserDataHost mUserDataHost = new UserDataHost();

    /**
     * @return {@link UserDataHost} that manages {@link UserData} objects attached to
     *         this Tab instance.
     */
    public UserDataHost getUserDataHost() {
        return mUserDataHost;
    }

    public Context getThemedApplicationContext() {
        return mThemedApplicationContext;
    }

    /**
     * Creates an instance of a {@link Tab}.
     *
     * This constructor may be called before the native library has been loaded, so any additions
     * must be vetted for library calls.
     *
     * @param id        The id this tab should be identified with.
     * @param incognito Whether or not this tab is incognito.
     * @param window    An instance of a {@link WindowAndroid}.
     */
    public Tab(int id, boolean incognito, WindowAndroid window) {
        this(id, INVALID_TAB_ID, incognito, window, null, null, null);
    }

    /**
     * Creates an instance of a {@link Tab}.
     *
     * This constructor can be called before the native library has been loaded, so any additions
     * must be vetted for library calls.
     *
     * @param id          The id this tab should be identified with.
     * @param parentId    The id id of the tab that caused this tab to be opened.
     * @param incognito   Whether or not this tab is incognito.
     * @param window      An instance of a {@link WindowAndroid}.
     * @param creationState State in which the tab is created, needed to initialize TabUma
     *                      accounting. When null, TabUma will not be initialized.
     * @param frozenState State containing information about this Tab, if it was persisted.
     */
    @SuppressLint("HandlerLeak")
    public Tab(int id, int parentId, boolean incognito, WindowAndroid window,
            @Nullable @TabLaunchType Integer type,
            @Nullable @TabCreationState Integer creationState, TabState frozenState) {
        mId = TabIdManager.getInstance().generateValidId(id);
        mParentId = parentId;
        mIncognito = incognito;
        mThemedApplicationContext = new ContextThemeWrapper(
                ContextUtils.getApplicationContext(), ChromeActivity.getThemeId());
        mWindowAndroid = window;
        mLaunchType = type;
        mLaunchTypeAtCreation = type;
        mIsDetached = getActivity() == null;

        Resources resources = mThemedApplicationContext.getResources();
        mIdealFaviconSize = resources.getDimensionPixelSize(R.dimen.default_favicon_size);

        TabThemeColorHelper.createForTab(this);

        // Restore data from the TabState, if it existed.
        if (frozenState != null) {
            assert type == TabLaunchType.FROM_RESTORE;
            restoreFieldsFromState(frozenState);
        } else {
            if (mParentId == INVALID_TAB_ID || getTabModelSelector() == null
                    || getTabModelSelector().getTabById(mParentId) == null) {
                mRootId = mId;
            } else {
                mRootId = getTabModelSelector().getTabById(mParentId).getRootId();
            }
        }

        addObserver(mTabObserver);
        addObserver(mFullscreenHandler);

        if (incognito) {
            CipherFactory.getInstance().triggerKeyGeneration();
        }

        ContextualSearchTabHelper.createForTab(this);
        MediaSessionTabHelper.createForTab(this);

        if (creationState != null) {
            TabUma.create(this, creationState);
            if (frozenState == null) {
                assert creationState != TabCreationState.FROZEN_ON_RESTORE;
            } else {
                assert type == TabLaunchType.FROM_RESTORE
                        && creationState == TabCreationState.FROZEN_ON_RESTORE;
            }
        }

        mAttachStateChangeListener = new OnAttachStateChangeListener() {
            @Override
            public void onViewAttachedToWindow(View view) {
                mIsViewAttachedToWindow = true;
                updateInteractableState();
            }

            @Override
            public void onViewDetachedFromWindow(View view) {
                mIsViewAttachedToWindow = false;
                updateInteractableState();
            }
        };
    }

    /**
     * Restores member fields from the given TabState.
     * @param state TabState containing information about this Tab.
     */
    private void restoreFieldsFromState(TabState state) {
        assert state != null;
        mAppAssociatedWith = state.openerAppId;
        mFrozenContentsState = state.contentsState;
        mShouldPreserve = state.shouldPreserve;
        mTimestampMillis = state.timestampMillis;
        mUrl = state.getVirtualUrlFromState();

        TabThemeColorHelper.get(this).updateFromTabState(state);
        mTitle = state.getDisplayTitleFromState();
        mIsTitleDirectionRtl = mTitle != null
                && LocalizationUtils.getFirstStrongCharacterDirection(mTitle)
                        == LocalizationUtils.RIGHT_TO_LEFT;
        mLaunchTypeAtCreation = state.tabLaunchTypeAtCreation;
        mRootId = state.rootId == Tab.INVALID_TAB_ID ? mId : state.rootId;
    }

    /**
     * Adds a {@link TabObserver} to be notified on {@link Tab} changes.
     * @param observer The {@link TabObserver} to add.
     */
    public void addObserver(TabObserver observer) {
        mObservers.addObserver(observer);
    }

    /**
     * Removes a {@link TabObserver}.
     * @param observer The {@link TabObserver} to remove.
     */
    public void removeObserver(TabObserver observer) {
        mObservers.removeObserver(observer);
    }

    /**
     * @return Whether or not this tab has a previous navigation entry.
     */
    public boolean canGoBack() {
        return getWebContents() != null && getWebContents().getNavigationController().canGoBack();
    }

    /**
     * @return Whether or not this tab has a navigation entry after the current one.
     */
    public boolean canGoForward() {
        return getWebContents() != null
                && getWebContents().getNavigationController().canGoForward();
    }

    /**
     * Goes to the navigation entry before the current one.
     */
    public void goBack() {
        if (getWebContents() != null) getWebContents().getNavigationController().goBack();
    }

    /**
     * Goes to the navigation entry after the current one.
     */
    public void goForward() {
        if (getWebContents() != null) getWebContents().getNavigationController().goForward();
    }

    /**
     * Loads the current navigation if there is a pending lazy load (after tab restore).
     */
    public void loadIfNecessary() {
        if (getWebContents() != null) getWebContents().getNavigationController().loadIfNecessary();
    }

    /**
     * Causes this tab to navigate to the specified URL.
     * @param params parameters describing the url load. Note that it is important to set correct
     *               page transition as it is used for ranking URLs in the history so the omnibox
     *               can report suggestions correctly.
     * @return FULL_PRERENDERED_PAGE_LOAD or PARTIAL_PRERENDERED_PAGE_LOAD if the page has been
     *         prerendered. DEFAULT_PAGE_LOAD if it had not.
     */
    public int loadUrl(LoadUrlParams params) {
        try {
            TraceEvent.begin("Tab.loadUrl");
            // TODO(tedchoc): When showing the android NTP, delay the call to nativeLoadUrl until
            //                the android view has entirely rendered.
            if (!mIsNativePageCommitPending) {
                mIsNativePageCommitPending = maybeShowNativePage(params.getUrl(), false);
            }

            // Clear the app association if the user navigated to a different page from the omnibox.
            if ((params.getTransitionType() & PageTransition.FROM_ADDRESS_BAR)
                    == PageTransition.FROM_ADDRESS_BAR) {
                mAppAssociatedWith = null;
                setIsAllowedToReturnToExternalApp(false);
            }
            if ("chrome://java-crash/".equals(params.getUrl())) {
                return handleJavaCrash();
            }

            if (mNativeTabAndroid == 0) {
                // if mNativeTabAndroid is null then we are going to crash anyways on the
                // native side. Lets crash on the java side so that we can have a better stack
                // trace.
                throw new RuntimeException("Tab.loadUrl called when no native side exists");
            }

            // We load the URL from the tab rather than directly from the ContentView so the tab has
            // a chance of using a prerenderer page is any.
            int loadType = nativeLoadUrl(mNativeTabAndroid, params.getUrl(),
                    params.getInitiatorOrigin(), params.getVerbatimHeaders(), params.getPostData(),
                    params.getTransitionType(),
                    params.getReferrer() != null ? params.getReferrer().getUrl() : null,
                    // Policy will be ignored for null referrer url, 0 is just a placeholder.
                    // TODO(ppi): Should we pass Referrer jobject and add JNI methods to read it
                    //            from the native?
                    params.getReferrer() != null ? params.getReferrer().getPolicy() : 0,
                    params.getIsRendererInitiated(), params.getShouldReplaceCurrentEntry(),
                    params.getHasUserGesture(), params.getShouldClearHistoryList(),
                    params.getInputStartTimestamp(), params.getIntentReceivedTimestamp());

            for (TabObserver observer : mObservers) {
                observer.onLoadUrl(this, params, loadType);
            }
            return loadType;
        } finally {
            TraceEvent.end("Tab.loadUrl");
        }
    }

    /**
     * Called when the contextual ActionBar is shown or hidden.
     * @param show {@code true} when the ActionBar is shown; {@code false} otherwise.
     */
    public void notifyContextualActionBarVisibilityChanged(boolean show) {
        for (TabObserver observer : mObservers) {
            observer.onContextualActionBarVisibilityChanged(this, show);
        }
    }

    /**
     * Throws a RuntimeException. Useful for testing crash reports with obfuscated Java stacktraces.
     */
    private int handleJavaCrash() {
        throw new RuntimeException("Intentional Java Crash");
    }

    /**
     * Load the original image (uncompressed by spdy proxy) in this tab.
     */
    void loadOriginalImage() {
        if (mNativeTabAndroid != 0) nativeLoadOriginalImage(mNativeTabAndroid);
    }

    /**
     * @return Whether or not the {@link Tab} is currently showing an interstitial page, such as
     *         a bad HTTPS page.
     */
    public boolean isShowingInterstitialPage() {
        return getWebContents() != null && getWebContents().isShowingInterstitialPage();
    }

    /**
     * @return Whether a tab modal dialog is showing.
     */
    public boolean isShowingTabModalDialog() {
        return mIsShowingTabModalDialog;
    }

    /**
     * @return Whether the {@link Tab} is currently showing an error page.
     */
    public boolean isShowingErrorPage() {
        return mIsShowingErrorPage;
    }

    /**
     * Sets whether the tab is showing an error page.  This is reset whenever the tab finishes a
     * navigation.
     *
     * @param isShowingErrorPage Whether the tab shows an error page.
     */
    public void setIsShowingErrorPage(boolean isShowingErrorPage) {
        mIsShowingErrorPage = isShowingErrorPage;
    }

    /**
     * @return Whether or not the tab has something valid to render.
     */
    public boolean isReady() {
        return mNativePage != null || (getWebContents() != null && getWebContents().isReady());
    }

    /**
     * @return The {@link View} displaying the current page in the tab. This can be {@code null}, if
     *         the tab is frozen or being initialized or destroyed.
     */
    public View getView() {
        return mNativePage != null ? mNativePage.getView() : mContentView;
    }

    /**
     * @return The width of the content of this tab.  Can be 0 if there is no content.
     */
    public int getWidth() {
        View view = getView();
        return view != null ? view.getWidth() : 0;
    }

    /**
     * @return The height of the content of this tab.  Can be 0 if there is no content.
     */
    public int getHeight() {
        View view = getView();
        return view != null ? view.getHeight() : 0;
    }

    /**
     * @return The application {@link Context} associated with this tab.
     */
    protected Context getApplicationContext() {
        return mThemedApplicationContext.getApplicationContext();
    }

    /**
     * @return {@link ChromeActivity} that currently contains this {@link Tab} in its
     *         {@link TabModel}.
     */
    public ChromeActivity getActivity() {
        if (getWindowAndroid() == null) return null;
        Activity activity = WindowAndroid.activityFromContext(
                getWindowAndroid().getContext().get());
        if (activity instanceof ChromeActivity) return (ChromeActivity) activity;
        return null;
    }

    /**
     * @return {@link TabModelSelector} that currently hosts the {@link TabModel} for this
     *         {@link Tab}.
     */
    public TabModelSelector getTabModelSelector() {
        if (getActivity() == null) return null;
        return getActivity().getTabModelSelector();
    }

    /** @return An opaque "state" object that can be persisted to storage. */
    public TabState getState() {
        if (!isInitialized()) return null;
        TabState tabState = new TabState();
        tabState.contentsState = getWebContentsState();
        tabState.openerAppId = mAppAssociatedWith;
        tabState.parentId = mParentId;
        tabState.shouldPreserve = mShouldPreserve;
        tabState.timestampMillis = mTimestampMillis;
        tabState.tabLaunchTypeAtCreation = mLaunchTypeAtCreation;
        tabState.themeColor = TabThemeColorHelper.getColor(this);
        tabState.rootId = mRootId;
        return tabState;
    }

    /** @return WebContentsState representing the state of the WebContents (navigations, etc.) */
    public WebContentsState getFrozenContentsState() {
        return mFrozenContentsState;
    }

    /** Returns an object representing the state of the Tab's WebContents. */
    private TabState.WebContentsState getWebContentsState() {
        if (mFrozenContentsState != null) return mFrozenContentsState;

        // Native call returns null when buffer allocation needed to serialize the state failed.
        ByteBuffer buffer = getWebContentsStateAsByteBuffer();
        if (buffer == null) return null;

        TabState.WebContentsState state = new TabState.WebContentsState(buffer);
        state.setVersion(TabState.CONTENTS_STATE_CURRENT_VERSION);
        return state;
    }

    /** Returns an ByteBuffer representing the state of the Tab's WebContents. */
    private ByteBuffer getWebContentsStateAsByteBuffer() {
        if (mPendingLoadParams == null) {
            return TabState.getContentsStateAsByteBuffer(this);
        } else {
            Referrer referrer = mPendingLoadParams.getReferrer();
            return TabState.createSingleNavigationStateAsByteBuffer(
                    mPendingLoadParams.getUrl(),
                    referrer != null ? referrer.getUrl() : null,
                    // Policy will be ignored for null referrer url, 0 is just a placeholder.
                    referrer != null ? referrer.getPolicy() : 0,
                    isIncognito());
        }
    }

    /**
     * Reloads the current page content.
     */
    public void reload() {
        // TODO(dtrainor): Should we try to rebuild the ContentView if it's frozen?
        if (OfflinePageUtils.isOfflinePage(this)) {
            // If current page is an offline page, reload it with custom behavior defined in extra
            // header respected.
            OfflinePageUtils.reload(this);
        } else {
            if (getWebContents() != null) getWebContents().getNavigationController().reload(true);
        }
    }

    /**
     * Reloads the current page content.
     * This version ignores the cache and reloads from the network.
     */
    public void reloadIgnoringCache() {
        if (getWebContents() != null) {
            getWebContents().getNavigationController().reloadBypassingCache(true);
        }
    }

    /** Stop the current navigation. */
    public void stopLoading() {
        if (isLoading()) {
            RewindableIterator<TabObserver> observers = getTabObservers();
            while (observers.hasNext()) {
                observers.next().onPageLoadFinished(this, getUrl());
            }
        }
        if (getWebContents() != null) getWebContents().stop();
    }

    /**
     * @return a value between 0 and 100 reflecting what percentage of the page load is complete.
     */
    public int getProgress() {
        if (!isLoading()) return 100;

        TabWebContentsDelegateAndroid delegate = getTabWebContentsDelegateAndroid();
        return delegate != null ? delegate.getMostRecentProgress() : 0;
    }

    /**
     * @return The background color of the tab.
     */
    public int getBackgroundColor() {
        if (mNativePage != null) return mNativePage.getBackgroundColor();
        if (getWebContents() != null) return getWebContents().getBackgroundColor();
        return Color.WHITE;
    }

    void notifyThemeColorChanged(int themeColor) {
        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) {
            observers.next().onDidChangeThemeColor(this, themeColor);
        }
    }

    /**
     * @return The web contents associated with this tab.
     */
    @Nullable
    public WebContents getWebContents() {
        return mWebContents;
    }

    /**
     * @return The profile associated with this tab.
     */
    public Profile getProfile() {
        if (mNativeTabAndroid == 0) return null;
        return nativeGetProfileAndroid(mNativeTabAndroid);
    }

    /**
     * For more information about the uniqueness of {@link #getId()} see comments on {@link Tab}.
     * @see Tab
     * @return The id representing this tab.
     */
    @CalledByNative
    public int getId() {
        return mId;
    }

    /**
     * This is used to change how this tab related to other tabs.
     * @param rootId New relationship id to be set.
     */
    public void setRootId(int rootId) {
        mRootId = rootId;
    }

    /**
     * @return Tab's relationship id.
     */
    public int getRootId() {
        return mRootId;
    }

    public boolean isIncognito() {
        return mIncognito;
    }

    /**
     * @return The {@link NativePage} associated with the current page, or {@code null} if there is
     *         no current page or the current page is displayed using something besides
     *         {@link NativePage}.
     */
    public NativePage getNativePage() {
        return mNativePage;
    }

    /**
     * @return Whether or not the {@link Tab} represents a {@link NativePage}.
     */
    @CalledByNative
    public boolean isNativePage() {
        return mNativePage != null;
    }

    /**
     * @return If the page being displayed is a Preview
     */
    public boolean isPreview() {
        return getWebContents() != null && !isNativePage() && !isShowingInterstitialPage()
                && getSecurityLevel() != ConnectionSecurityLevel.DANGEROUS
                && PreviewsAndroidBridge.getInstance().shouldShowPreviewUI(getWebContents());
    }

    /**
     * @return The current {@link ConnectionSecurityLevel} for the tab.
     */
    // TODO(tedchoc): Remove this and transition all clients to use LocationBarModel directly.
    public int getSecurityLevel() {
        return SecurityStateModel.getSecurityLevelForWebContents(getWebContents());
    }

    /**
     * @return An {@link ObserverList.RewindableIterator} instance that points to all of
     *         the current {@link TabObserver}s on this class.  Note that calling
     *         {@link java.util.Iterator#remove()} will throw an
     *         {@link UnsupportedOperationException}.
     */
    protected ObserverList.RewindableIterator<TabObserver> getTabObservers() {
        return mObservers.rewindableIterator();
    }

    /**
     * Called on the foreground tab when the Activity showing the Tab gets started. This is called
     * on both cold and warm starts.
     */
    public void onActivityShown() {
        if (isHidden()) {
            show(TabSelectionType.FROM_USER);
        } else {
            // The visible Tab's renderer process may have died after the activity was paused.
            // Ensure that it's restored appropriately.
            loadIfNeeded();
        }

        // When resuming the activity, force an update to the fullscreen state to ensure a
        // subactivity did not change the fullscreen configuration of this ChromeTab's renderer in
        // the case where it was shared.
        updateFullscreenEnabledState();
    }

    /**
     * Called on the foreground tab when the Activity showing the Tab gets stopped.
     */
    public void onActivityHidden() {
        hide(TabHidingType.ACTIVITY_HIDDEN);
    }

    /**
     * Prepares the tab to be shown. This method is supposed to be called before the tab is
     * displayed. It restores the ContentView if it is not available after the cold start and
     * reloads the tab if its renderer has crashed.
     * @param type Specifies how the tab was selected.
     */
    public final void show(@TabSelectionType int type) {
        try {
            TraceEvent.begin("Tab.show");
            if (!isHidden()) return;
            // Keep unsetting mIsHidden above loadIfNeeded(), so that we pass correct visibility
            // when spawning WebContents in loadIfNeeded().
            mIsHidden = false;
            updateInteractableState();

            loadIfNeeded();
            assert !isFrozen();

            if (getWebContents() != null) getWebContents().onShow();

            // If the NativePage was frozen while in the background (see NativePageAssassin),
            // recreate the NativePage now.
            NativePage nativePage = getNativePage();
            if (nativePage instanceof FrozenNativePage) {
                maybeShowNativePage(nativePage.getUrl(), true);
            }
            NativePageAssassin.getInstance().tabShown(this);
            TabImportanceManager.tabShown(this);

            // If the page is still loading, update the progress bar (otherwise it would not show
            // until the renderer notifies of new progress being made).
            if (getProgress() < 100 && !isShowingInterstitialPage()) {
                notifyLoadProgress(getProgress());
            }

            for (TabObserver observer : mObservers) observer.onShown(this, type);

            // Updating the timestamp has to happen after the showInternal() call since subclasses
            // may use it for logging.
            mTimestampMillis = System.currentTimeMillis();
        } finally {
            TraceEvent.end("Tab.show");
        }
    }

    /**
     * Triggers the hiding logic for the view backing the tab.
     */
    public final void hide(@TabHidingType int type) {
        try {
            TraceEvent.begin("Tab.hide");
            if (isHidden()) return;
            mIsHidden = true;
            updateInteractableState();

            if (getWebContents() != null) getWebContents().onHide();

            // Clean up any fullscreen state that might impact other tabs.
            if (mFullscreenManager != null) {
                mFullscreenManager.exitPersistentFullscreenMode();
            }

            // Allow this tab's NativePage to be frozen if it stays hidden for a while.
            NativePageAssassin.getInstance().tabHidden(this);

            for (TabObserver observer : mObservers) observer.onHidden(this, type);
        } finally {
            TraceEvent.end("Tab.hide");
        }
    }

    /* package */ final void setImportance(@ChildProcessImportance int importance) {
        if (mImportance == importance) return;
        mImportance = importance;
        WebContents webContents = getWebContents();
        if (webContents == null) return;
        webContents.setImportance(mImportance);
    }

    /**
     * Shows the given {@code nativePage} if it's not already showing.
     * @param nativePage The {@link NativePage} to show.
     */
    private void showNativePage(NativePage nativePage) {
        if (mNativePage == nativePage) return;
        NativePage previousNativePage = mNativePage;
        if (mNativePage != null && !(mNativePage instanceof FrozenNativePage)) {
            mNativePage.getView().removeOnAttachStateChangeListener(mAttachStateChangeListener);
        }
        mNativePage = nativePage;
        if (mNativePage != null && !(mNativePage instanceof FrozenNativePage)) {
            mNativePage.getView().addOnAttachStateChangeListener(mAttachStateChangeListener);
        }
        pushNativePageStateToNavigationEntry();
        notifyContentChanged();
        destroyNativePageInternal(previousNativePage);
    }

    /**
     * Replaces the current NativePage with a empty stand-in for a NativePage. This can be used
     * to reduce memory pressure.
     */
    public void freezeNativePage() {
        if (mNativePage == null || mNativePage instanceof FrozenNativePage) return;
        assert mNativePage.getView().getParent() == null : "Cannot freeze visible native page";
        mNativePage = FrozenNativePage.freeze(mNativePage);
        updateInteractableState();
    }

    /**
     * Hides the current {@link NativePage}, if any, and shows the {@link WebContents}'s view.
     */
    protected void showRenderedPage() {
        updateTitle();

        if (mNativePage == null) return;
        NativePage previousNativePage = mNativePage;
        if (!(mNativePage instanceof FrozenNativePage)) {
            mNativePage.getView().removeOnAttachStateChangeListener(mAttachStateChangeListener);
        }
        mNativePage = null;
        notifyContentChanged();
        destroyNativePageInternal(previousNativePage);
    }

    /**
     * Initializes {@link Tab} with {@code webContents}.  If {@code webContents} is {@code null} a
     * new {@link WebContents} will be created for this {@link Tab}.
     * @param webContents       A {@link WebContents} object or {@code null} if one should be
     *                          created.
     * @param tabContentManager A {@link TabContentManager} instance or {@code null} if the web
     *                          content will be managed/displayed manually.
     * @param delegateFactory   The {@link TabDelegateFactory} to be used for delegate creation.
     * @param initiallyHidden   Only used if {@code webContents} is {@code null}.  Determines
     *                          whether or not the newly created {@link WebContents} will be hidden
     *                          or not.
     * @param unfreeze          Whether there should be an attempt to restore state at the end of
     *                          the initialization.
     */
    public void initialize(WebContents webContents, TabContentManager tabContentManager,
            TabDelegateFactory delegateFactory, boolean initiallyHidden, boolean unfreeze) {
        try {
            TraceEvent.begin("Tab.initialize");

            mDelegateFactory = delegateFactory;
            initializeNative();

            RevenueStats.getInstance().tabCreated(this);

            mBrowserControlsVisibilityDelegate =
                    mDelegateFactory.createBrowserControlsVisibilityDelegate(this);

            // Attach the TabContentManager if we have one.  This will bind this Tab's content layer
            // to this manager.
            // TODO(dtrainor): Remove this and move to a pull model instead of pushing the layer.
            attachTabContentManager(tabContentManager);

            // If there is a frozen WebContents state or a pending lazy load, don't create a new
            // WebContents.
            if (getFrozenContentsState() != null || getPendingLoadParams() != null) {
                if (unfreeze) unfreezeContents();
                return;
            }

            boolean creatingWebContents = webContents == null;
            if (creatingWebContents) {
                webContents = WarmupManager.getInstance().takeSpareWebContents(
                        isIncognito(), initiallyHidden);
                if (webContents == null) {
                    webContents =
                            WebContentsFactory.createWebContents(isIncognito(), initiallyHidden);
                }
            }

            initWebContents(webContents);

            if (!creatingWebContents && webContents.isLoadingToDifferentDocument()) {
                didStartPageLoad(webContents.getVisibleUrl());
            }

        } finally {
            if (mTimestampMillis == INVALID_TIMESTAMP) {
                mTimestampMillis = System.currentTimeMillis();
            }

            TraceEvent.end("Tab.initialize");
        }
    }

    /**
     * Begins the tab reparenting process. Detaches the tab from its current activity and fires
     * an Intent to reparent the tab into its new host activity.
     *
     * @param intent An optional intent with the desired component, flags, or extras to use when
     *               launching the new host activity. This intent's URI and action will be
     *               overriden. This may be null if no intent customization is needed.
     * @param startActivityOptions Options to pass to {@link Activity#startActivity(Intent, Bundle)}
     * @param finalizeCallback A callback that will be called after the tab is attached to the new
     *                         host activity in {@link #attachAndFinishReparenting}.
     * @return Whether reparenting succeeded. If false, the tab was not removed and the intent was
     *         not fired.
     */
    public boolean detachAndStartReparenting(Intent intent, Bundle startActivityOptions,
            Runnable finalizeCallback) {
        ChromeActivity activity = getActivity();
        if (activity == null) return false;

        if (intent == null) intent = new Intent();
        if (intent.getComponent() == null) {
            intent.setClass(mThemedApplicationContext, ChromeLauncherActivity.class);
        }
        intent.setAction(Intent.ACTION_VIEW);
        if (TextUtils.isEmpty(intent.getDataString())) intent.setData(Uri.parse(getUrl()));
        if (isIncognito()) {
            intent.putExtra(Browser.EXTRA_APPLICATION_ID,
                    ContextUtils.getApplicationContext().getPackageName());
            intent.putExtra(IntentHandler.EXTRA_OPEN_NEW_INCOGNITO_TAB, true);
        }
        IntentHandler.addTrustedIntentExtras(intent);

        if (ChromeFeatureList.isEnabled(ChromeFeatureList.TAB_REPARENTING)) {
            // Add the tab to AsyncTabParamsManager before removing it from the current model to
            // ensure the global count of tabs is correct. See https://crbug.com/611806.
            intent.putExtra(IntentHandler.EXTRA_TAB_ID, mId);
            AsyncTabParamsManager.add(
                    mId, new TabReparentingParams(this, intent, finalizeCallback));

            detach();
        }

        activity.startActivity(intent, startActivityOptions);
        return true;
    }

    /**
     * Detaches a tab from its current activity if any.
     *
     * In details, this function:
     * - Tags the tab using mIsDetached.
     * - Removes the tab from its current {@link TabModelSelector}, effectively severing
     *   the {@link Activity} to {@link Tab} link.
     */
    private void detach() {
        mIsDetached = true;

        TabModelSelector tabModelSelector = getTabModelSelector();
        if (tabModelSelector != null) {
            tabModelSelector.getModel(mIncognito).removeTab(this);
        }
        // TODO(yusufo): We can't call updateWindowAndroid here and set mWindowAndroid to null
        // because many code paths (including navigation) expect the tab to always be associated
        // with an activity, and will crash. crbug.com/657007
        WebContents webContents = getWebContents();
        if (webContents != null) webContents.setTopLevelNativeWindow(null);
        attachTabContentManager(null);

        for (TabObserver observer : mObservers) {
            observer.onActivityAttachmentChanged(this, false);
        }
    }

    /**
     * Finishes the tab reparenting process. Attaches the tab to the new activity, and updates the
     * tab and related objects to reference the new activity. This updates many delegates inside the
     * tab and {@link WebContents} both on java and native sides.
     *
     * @param activity The new activity this tab should be associated with.
     * @param tabDelegateFactory The new delegate factory this tab should be using.
     * @param finalizeCallback A Callback to be called after the Tab has been reparented.
     */
    public void attachAndFinishReparenting(ChromeActivity activity,
            TabDelegateFactory tabDelegateFactory,
            @Nullable Runnable finalizeCallback) {
        // TODO(yusufo): Share these calls with the construction related calls.
        // crbug.com/590281
        activity.getCompositorViewHolder().prepareForTabReparenting();

        attach(activity, tabDelegateFactory);

        mIsTabStateDirty = true;

        if (finalizeCallback != null) finalizeCallback.run();
    }

    /**
     * Attaches the tab to the new activity and updates the tab and related objects to reference the
     * new activity. This updates many delegates inside the tab and {@link WebContents} both on
     * java and native sides.
     * TODO(ltian:) explore calling this for all types of tabs.
     *
     * @param activity  The new activity this tab should be associated with.
     * @param tabDelegateFactory  The new delegate factory this tab should be using.
     */
    public void attach(ChromeActivity activity, TabDelegateFactory tabDelegateFactory) {
        assert mIsDetached;
        updateWindowAndroid(activity.getWindowAndroid());

        // Update for the controllers that need the Compositor from the new Activity.
        attachTabContentManager(activity.getTabContentManager());
        mFullscreenManager = activity.getFullscreenManager();
        // Update the delegate factory, then recreate and propagate all delegates.
        mDelegateFactory = tabDelegateFactory;
        mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);
        mBrowserControlsVisibilityDelegate =
                mDelegateFactory.createBrowserControlsVisibilityDelegate(this);

        mIsDetached = false;

        // Reload the NativePage (if any), since the old NativePage has a reference to the old
        // activity.
        maybeShowNativePage(getUrl(), true);

        nativeAttachDetachedTab(mNativeTabAndroid);

        if (getWebContents() != null) {
            nativeUpdateDelegates(mNativeTabAndroid, mWebContentsDelegate,
                    new TabContextMenuPopulator(
                            mDelegateFactory.createContextMenuPopulator(this), this));
            setInterceptNavigationDelegate(
                    mDelegateFactory.createInterceptNavigationDelegate(this));
            getAppBannerManager().setIsEnabledForTab(mDelegateFactory.canShowAppBanners(this));
        }

        for (TabObserver observer : mObservers) {
            observer.onActivityAttachmentChanged(this, true);
        }
    }

    /**
     * Update and propagate the new WindowAndroid.
     * @param windowAndroid The WindowAndroid to propagate.
     */
    public void updateWindowAndroid(WindowAndroid windowAndroid) {
        // TODO(yusufo): mWindowAndroid can never be null until crbug.com/657007 is fixed.
        assert windowAndroid != null;
        mWindowAndroid = windowAndroid;
        WebContents webContents = getWebContents();
        if (webContents != null) webContents.setTopLevelNativeWindow(mWindowAndroid);
    }

    /**
     * @return Whether the tab is detached from any Activity and its {@link WindowAndroid}.
     * Certain functionalities will not work until it is attached to an activity
     * with {@link Tab#attachAndFinishReparenting}.
     */
    public boolean isDetached() {
        return mIsDetached;
    }

    /**
     * Attach the content layer for this tab to the given {@link TabContentManager}.
     * @param tabContentManager {@link TabContentManager} to attach to.
     */
    public void attachTabContentManager(TabContentManager tabContentManager) {
        if (mNativeTabAndroid == 0) return;
        nativeAttachToTabContentManager(mNativeTabAndroid, tabContentManager);
    }

    void clearThumbnailPlaceholder() {
        if (mNativeTabAndroid != 0) nativeClearThumbnailPlaceholder(mNativeTabAndroid);
    }

    /**
     * @return The delegate factory for testing purposes only.
     */
    public TabDelegateFactory getDelegateFactory() {
        return mDelegateFactory;
    }

    /**
     * @return Content view used for rendered web contents. Can be null
     *    if web contents is null.
     */
    public ViewGroup getContentView() {
        return mContentView;
    }

    /**
     * Called when a navigation begins and no navigation was in progress
     * @param toDifferentDocument Whether this navigation will transition between
     * documents (i.e., not a fragment navigation or JS History API call).
     */
    protected void onLoadStarted(boolean toDifferentDocument) {
        if (toDifferentDocument) mIsLoading = true;
        for (TabObserver observer : mObservers) observer.onLoadStarted(this, toDifferentDocument);
    }

    /**
     * Called when a navigation completes and no other navigation is in progress.
     */
    protected void onLoadStopped() {
        // mIsLoading should only be false if this is a same-document navigation.
        boolean toDifferentDocument = mIsLoading;
        mIsLoading = false;
        for (TabObserver observer : mObservers) observer.onLoadStopped(this, toDifferentDocument);
    }

    /**
     * Called when a page has started loading.
     * @param validatedUrl URL being loaded.
     */
    protected void didStartPageLoad(String validatedUrl) {
        updateTitle();
        if (mIsRendererUnresponsive) handleRendererResponsiveStateChanged(true);

        for (TabObserver observer : mObservers) observer.onPageLoadStarted(this, validatedUrl);
    }

    /**
     * Called when a page has finished loading.
     * @param url URL that was loaded.
     */
    protected void didFinishPageLoad(String url) {
        mIsTabStateDirty = true;
        updateTitle();
        updateFullscreenEnabledState();

        for (TabObserver observer : mObservers) observer.onPageLoadFinished(this, url);
        mIsBeingRestored = false;
    }

    /**
     * Called when a page has failed loading.
     * @param errorCode The error code causing the page to fail loading.
     */
    protected void didFailPageLoad(int errorCode) {
        for (TabObserver observer : mObservers) {
            observer.onPageLoadFailed(this, errorCode);
        }
        mIsBeingRestored = false;
    }

    /**
     * Builds the native counterpart to this class.  Meant to be overridden by subclasses to build
     * subclass native counterparts instead.  Subclasses should not call this via super and instead
     * rely on the native class to create the JNI association.
     *
     * TODO(dfalcantara): Make this function harder to access.
     */
    public void initializeNative() {
        if (mNativeTabAndroid == 0) nativeInit();
        assert mNativeTabAndroid != 0;
        mIsInitialized = true;
    }

    /**
     * initializes the {@link WebContents}.
     *
     * @param webContents The WebContents object that will initialize all the browser components.
     */
    protected void initWebContents(WebContents webContents) {
        ContentView cv = ContentView.createContentView(mThemedApplicationContext, webContents);
        cv.setContentDescription(mThemedApplicationContext.getResources().getString(
                R.string.accessibility_content_view));
        webContents.initialize(PRODUCT_VERSION, new TabViewAndroidDelegate(this, cv), cv,
                getWindowAndroid(), WebContents.createDefaultInternalsHolder());
        SelectionPopupController.fromWebContents(webContents)
                .setActionModeCallback(new ChromeActionModeCallback(this, webContents));
        initBrowserComponents(webContents);
    }

    /**
     * Completes the browser content components initialization around a native WebContents
     * pointer. {@link #getNativePage()} will still return the {@link NativePage} if there is one.
     * All initialization that needs to reoccur after a web contents swap should be added here.
     * <p />
     * NOTE: If you attempt to pass a native WebContents that does not have the same incognito
     * state as this tab this call will fail.
     *
     * @param webContents The new web contents.
     */
    private void initBrowserComponents(WebContents webContents) {
        try {
            TraceEvent.begin("ChromeTab.initBrowserComponents");
            NativePage previousNativePage = mNativePage;
            mNativePage = null;
            destroyNativePageInternal(previousNativePage);

            WebContents oldWebContents = mWebContents;
            if (oldWebContents != null) {
                oldWebContents.setImportance(ChildProcessImportance.NORMAL);
                getWebContentsAccessibility(oldWebContents).setObscuredByAnotherView(false);
            }

            mWebContents = webContents;
            ContentUtils.setUserAgentOverride(mWebContents);
            mContentView = mWebContents.getViewAndroidDelegate().getContainerView();

            mWebContents.setImportance(mImportance);
            mContentView.setOnHierarchyChangeListener(this);
            mContentView.setOnSystemUiVisibilityChangeListener(this);

            mContentView.addOnAttachStateChangeListener(mAttachStateChangeListener);
            updateInteractableState();
            mWebContentsDelegate = mDelegateFactory.createWebContentsDelegate(this);
            TabWebContentsObserver.from(this);

            int parentId = getParentId();
            if (parentId != INVALID_TAB_ID) {
                Tab parentTab = getTabModelSelector().getTabById(parentId);
                if (parentTab != null && parentTab.isIncognito() != isIncognito()) {
                    parentId = INVALID_TAB_ID;
                }
            }

            assert mNativeTabAndroid != 0;
            nativeInitWebContents(mNativeTabAndroid, mIncognito, mIsDetached, webContents, parentId,
                    mWebContentsDelegate,
                    new TabContextMenuPopulator(
                            mDelegateFactory.createContextMenuPopulator(this), this));

            TabGestureStateListener.from(this, this::getFullscreenManager);

            // The InfoBarContainer needs to be created after the ContentView has been natively
            // initialized.
            // In the case where restoring a Tab or showing a prerendered one we already have a
            // valid infobar container, no need to recreate one.
            InfoBarContainer.from(this);

            SwipeRefreshHandler.from(this);

            notifyContentChanged();

            // For browser tabs, we want to set accessibility focus to the page
            // when it loads. This is not the default behavior for embedded
            // web views.
            getWebContentsAccessibility(getWebContents()).setShouldFocusOnPageLoad(true);

            ImeAdapter.fromWebContents(mWebContents).addEventObserver(new ImeEventObserver() {
                @Override
                public void onImeEvent() {
                    // Some text was set in the page. Don't reuse it if a tab is
                    // open from the same external application, we might lose some
                    // user data.
                    mAppAssociatedWith = null;
                }

                @Override
                public void onNodeAttributeUpdated(boolean editable, boolean password) {
                    if (getFullscreenManager() == null) return;
                    updateFullscreenEnabledState();
                }
            });

            setInterceptNavigationDelegate(mDelegateFactory.createInterceptNavigationDelegate(
                    this));

            getAppBannerManager().setIsEnabledForTab(mDelegateFactory.canShowAppBanners(this));
        } finally {
            TraceEvent.end("ChromeTab.initBrowserComponents");
        }
    }

    private static WebContentsAccessibility getWebContentsAccessibility(WebContents webContents) {
        return webContents != null ? WebContentsAccessibility.fromWebContents(webContents) : null;
    }

    /**
     * Shows a native page for url if it's a valid chrome-native URL. Otherwise, does nothing.
     * @param url The url of the current navigation.
     * @param forceReload If true, the current native page (if any) will not be reused, even if it
     *                    matches the URL.
     * @return True, if a native page was displayed for url.
     */
    boolean maybeShowNativePage(String url, boolean forceReload) {
        // While detached for reparenting we don't have an owning Activity, or TabModelSelector,
        // so we can't create the native page. The native page will be created once reparenting is
        // completed.
        if (mIsDetached) return false;
        NativePage candidateForReuse = forceReload ? null : getNativePage();
        NativePage nativePage = NativePageFactory.createNativePageForURL(url, candidateForReuse,
                this, getTabModelSelector(), getActivity());
        if (nativePage != null) {
            showNativePage(nativePage);
            notifyPageTitleChanged();
            notifyFaviconChanged();
            return true;
        }
        return false;
    }

    /**
     * Update internal Tab state when provisional load gets committed.
     * @param url The URL that was loaded.
     * @param transitionType The transition type to the current URL.
     */
    void handleDidFinishNavigation(String url, Integer transitionType) {
        mIsNativePageCommitPending = false;
        boolean isReload = (transitionType != null
                && (transitionType & PageTransition.CORE_MASK) == PageTransition.RELOAD);
        if (!maybeShowNativePage(url, isReload)) {
            showRenderedPage();
        }

        if (getInterceptNavigationDelegate() != null) {
            getInterceptNavigationDelegate().maybeUpdateNavigationHistory();
        }
    }

    /**
     * Calls onContentChanged on all TabObservers and updates accessibility visibility.
     */
    void notifyContentChanged() {
        for (TabObserver observer : mObservers) observer.onContentChanged(this);
        updateAccessibilityVisibility();
    }

    /**
     * Cleans up all internal state, destroying any {@link NativePage} or {@link WebContents}
     * currently associated with this {@link Tab}.  This also destroys the native counterpart
     * to this class, which means that all subclasses should erase their native pointers after
     * this method is called.  Once this call is made this {@link Tab} should no longer be used.
     */
    public void destroy() {
        mIsInitialized = false;
        // Update the title before destroying the tab. http://b/5783092
        updateTitle();

        for (TabObserver observer : mObservers) observer.onDestroyed(this);
        mObservers.clear();

        mUserDataHost.destroy();

        NativePage currentNativePage = mNativePage;
        mNativePage = null;
        destroyNativePageInternal(currentNativePage);
        destroyWebContents(true);

        TabImportanceManager.tabDestroyed(this);

        // Destroys the native tab after destroying the ContentView but before destroying the
        // InfoBarContainer. The native tab should be destroyed before the infobar container as
        // destroying the native tab cleanups up any remaining infobars. The infobar container
        // expects all infobars to be cleaned up before its own destruction.
        assert mNativeTabAndroid != 0;
        nativeDestroy(mNativeTabAndroid);
        assert mNativeTabAndroid == 0;
    }

    /**
     * @return Whether or not this Tab has a live native component.  This will be true prior to
     *         {@link #initializeNative()} being called or after {@link #destroy()}.
     */
    public boolean isInitialized() {
        return mIsInitialized;
    }

    /**
     * @return The URL that is currently visible in the location bar. This may not be the same as
     *         the last committed URL if a new navigation is in progress.
     */
    @CalledByNative
    public String getUrl() {
        String url = getWebContents() != null ? getWebContents().getVisibleUrl() : "";

        // If we have a ContentView, or a NativePage, or the url is not empty, we have a WebContents
        // so cache the WebContent's url. If not use the cached version.
        if (getWebContents() != null || isNativePage() || !TextUtils.isEmpty(url)) {
            mUrl = url;
        }

        return mUrl != null ? mUrl : "";
    }

    /**
     * @return The tab title.
     */
    @CalledByNative
    public String getTitle() {
        if (mTitle == null) updateTitle();
        return mTitle;
    }

    void updateTitle() {
        if (isFrozen()) return;

        // When restoring the tabs, the title will no longer be populated, so request it from the
        // WebContents or NativePage (if present).
        String title = "";
        if (isNativePage()) {
            title = mNativePage.getTitle();
        } else if (getWebContents() != null) {
            title = getWebContents().getTitle();
        }
        updateTitle(title);
    }

    /**
     * Cache the title for the current page.
     *
     * {@link ContentViewClient#onUpdateTitle} is unreliable, particularly for navigating backwards
     * and forwards in the history stack, so pull the correct title whenever the page changes.
     * onUpdateTitle is only called when the title of a navigation entry changes. When the user goes
     * back a page the navigation entry exists with the correct title, thus the title is not
     * actually changed, and no notification is sent.
     * @param title Title of the page.
     */
    void updateTitle(String title) {
        if (TextUtils.equals(mTitle, title)) return;

        mIsTabStateDirty = true;
        mTitle = title;
        mIsTitleDirectionRtl = LocalizationUtils.getFirstStrongCharacterDirection(title)
                == LocalizationUtils.RIGHT_TO_LEFT;
        notifyPageTitleChanged();
    }

    private void notifyPageTitleChanged() {
        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) {
            observers.next().onTitleUpdated(this);
        }
    }

    /**
     * Notify the observers that the load progress has changed.
     * @param progress The current percentage of progress.
     */
    protected void notifyLoadProgress(int progress) {
        for (TabObserver observer : mObservers) observer.onLoadProgressChanged(Tab.this, progress);
    }

    private void notifyFaviconChanged() {
        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) {
            observers.next().onFaviconUpdated(this, null);
        }
    }

    /**
     * @return True if the tab title should be displayed from right to left.
     */
    public boolean isTitleDirectionRtl() {
        return mIsTitleDirectionRtl;
    }

    /**
     * @return The bitmap of the favicon scaled to 16x16dp. null if no favicon
     *         is specified or it requires the default favicon.
     */
    public Bitmap getFavicon() {
        // If we have no content or a native page, return null.
        if (isNativePage() || getWebContents() == null) return null;

        // Use the cached favicon only if the page wasn't changed.
        if (mFavicon != null && mFaviconUrl != null && mFaviconUrl.equals(getUrl())) {
            return mFavicon;
        }

        return nativeGetFavicon(mNativeTabAndroid);
    }

    /**
     * Loads the tab if it's not loaded (e.g. because it was killed in background).
     * This will trigger a regular load for tabs with pending lazy first load (tabs opened in
     * background on low-memory devices).
     * @return true iff the Tab handled the request.
     */
    public boolean loadIfNeeded() {
        if (getActivity() == null) {
            Log.e(TAG, "Tab couldn't be loaded because Context was null.");
            return false;
        }

        if (mPendingLoadParams != null) {
            assert isFrozen();
            initWebContents(WebContentsFactory.createWebContents(isIncognito(), isHidden()));
            loadUrl(mPendingLoadParams);
            mPendingLoadParams = null;
            return true;
        }

        restoreIfNeeded();
        return true;
    }

    /**
     * Loads a tab that was already loaded but since then was lost. This happens either when we
     * unfreeze the tab from serialized state or when we reload a tab that crashed. In both cases
     * the load codepath is the same (run in loadIfNecessary()) and the same caching policies of
     * history load are used.
     */
    private final void restoreIfNeeded() {
        try {
            TraceEvent.begin("Tab.restoreIfNeeded");
            if (isFrozen() && mFrozenContentsState != null) {
                // Restore is needed for a tab that is loaded for the first time. WebContents will
                // be restored from a saved state.
                unfreezeContents();
            } else if (!needsReload()) {
                return;
            }

            loadIfNecessary();
            mIsBeingRestored = true;
            for (TabObserver observer : mObservers) observer.onRestoreStarted(this);
        } finally {
            TraceEvent.end("Tab.restoreIfNeeded");
        }
    }

    /**
     * Restores the WebContents from its saved state.  This should only be called if the tab is
     * frozen with a saved TabState, and NOT if it was frozen for a lazy load.
     * @return Whether or not the restoration was successful.
     */
    private void unfreezeContents() {
        try {
            TraceEvent.begin("Tab.unfreezeContents");
            assert mFrozenContentsState != null;

            WebContents webContents =
                    mFrozenContentsState.restoreContentsFromByteBuffer(isHidden());
            boolean failedToRestore = false;
            if (webContents == null) {
                // State restore failed, just create a new empty web contents as that is the best
                // that can be done at this point. TODO(jcivelli) http://b/5910521 - we should show
                // an error page instead of a blank page in that case (and the last loaded URL).
                webContents = WebContentsFactory.createWebContents(isIncognito(), isHidden());
                TabUma.create(this, TabCreationState.FROZEN_ON_RESTORE_FAILED);
                failedToRestore = true;
            }
            View compositorView = getActivity().getCompositorViewHolder();
            webContents.setSize(compositorView.getWidth(), compositorView.getHeight());

            mFrozenContentsState = null;
            initWebContents(webContents);

            if (failedToRestore) {
                String url = TextUtils.isEmpty(mUrl) ? UrlConstants.NTP_URL : mUrl;
                loadUrl(new LoadUrlParams(url, PageTransition.GENERATED));
            }
        } finally {
            TraceEvent.end("Tab.unfreezeContents");
        }
    }

    /**
     * @return Whether or not the tab is hidden.
     */
    public boolean isHidden() {
        return mIsHidden;
    }

    /**
     * @return Whether the tab can currently be interacted with by the user.  This requires the
     *         view owned by the Tab to be visible and in a state where the user can interact with
     *         it (i.e. not in something like the phone tab switcher).
     */
    @CalledByNative
    public boolean isUserInteractable() {
        return mInteractableState;
    }

    /**
     * Update the interactable state of the tab. If the state has changed, it will call the
     * {@link #onInteractableStateChanged(boolean)} method.
     */
    private void updateInteractableState() {
        boolean currentState = !mIsHidden && !isFrozen()
                && (mIsViewAttachedToWindow || VrModuleProvider.getDelegate().isInVr());

        if (currentState == mInteractableState) return;

        mInteractableState = currentState;
        onInteractableStateChanged(currentState);
    }

    /**
     * A notification that the interactability of this tab has changed.
     * @param interactable Whether the tab is interactable.
     */
    private void onInteractableStateChanged(boolean interactable) {
        for (TabObserver observer : mObservers) observer.onInteractabilityChanged(interactable);
    }

    /**
     * @return Whether or not the tab is in the closing process.
     */
    public boolean isClosing() {
        return mIsClosing;
    }

    /**
     * @param closing Whether or not the tab is in the closing process.
     */
    public void setClosing(boolean closing) {
        mIsClosing = closing;

        for (TabObserver observer : mObservers) observer.onClosingStateChanged(this, closing);
    }

    /**
     * @return Whether the Tab has requested a reload.
     */
    public boolean needsReload() {
        return getWebContents() != null && getWebContents().getNavigationController().needsReload();
    }

    /**
     * Set whether the Tab needs to be reloaded.
     */
    protected void setNeedsReload() {
        assert getWebContents() != null;
        getWebContents().getNavigationController().setNeedsReload();
    }

    /**
     * @return true iff the tab is loading and an interstitial page is not showing.
     */
    public boolean isLoading() {
        return mIsLoading && !isShowingInterstitialPage();
    }

    /**
     * @return true iff the tab is performing a restore page load.
     */
    public boolean isBeingRestored() {
        return mIsBeingRestored;
    }

    /**
     * @return The id of the tab that caused this tab to be opened.
     */
    public int getParentId() {
        return mParentId;
    }

    /**
     * @return Whether the tab should be grouped with its parent tab (true by default).
     */
    public boolean isGroupedWithParent() {
        return mGroupedWithParent;
    }

    /**
     * Sets whether the tab should be grouped with its parent tab.
     *
     * @param groupedWithParent The new value.
     * @see #isGroupedWithParent
     */
    public void setGroupedWithParent(boolean groupedWithParent) {
        mGroupedWithParent = groupedWithParent;
    }

    private void destroyNativePageInternal(NativePage nativePage) {
        if (nativePage == null) return;
        assert nativePage != mNativePage : "Attempting to destroy active page.";

        nativePage.destroy();
    }

    /**
     * Called when the background color for the content changes.
     * @param color The current for the background.
     */
    void onBackgroundColorChanged(int color) {
        for (TabObserver observer : mObservers) observer.onBackgroundColorChanged(this, color);
    }

    /**
     * Destroys the current {@link WebContents}.
     * @param deleteNativeWebContents Whether or not to delete the native WebContents pointer.
     */
    private final void destroyWebContents(boolean deleteNativeWebContents) {
        if (mWebContents == null) return;

        mContentView.setOnHierarchyChangeListener(null);
        mContentView.setOnSystemUiVisibilityChangeListener(null);
        mContentView.removeOnAttachStateChangeListener(mAttachStateChangeListener);
        mContentView = null;
        updateInteractableState();

        mWebContents = null;
        mWebContentsDelegate = null;

        assert mNativeTabAndroid != 0;
        nativeDestroyWebContents(mNativeTabAndroid, deleteNativeWebContents);
    }

    /**
     * @return The {@link WindowAndroid} associated with this {@link Tab}.
     */
    public WindowAndroid getWindowAndroid() {
        return mWindowAndroid;
    }

    /**
     * @return The current {@link TabWebContentsDelegateAndroid} instance.
     */
    public TabWebContentsDelegateAndroid getTabWebContentsDelegateAndroid() {
        return mWebContentsDelegate;
    }

    private boolean isIdealFaviconSize(int width, int height) {
        return width == mIdealFaviconSize && height == mIdealFaviconSize;
    }

    /**
     * @param width new favicon's width.
     * @param height new favicon's height.
     * @return true iff the new favicon should replace the current one.
     */
    private boolean isBetterFavicon(int width, int height) {
        if (isIdealFaviconSize(width, height)) return true;

        // Prefer square favicons over rectangular ones
        if (mFaviconWidth != mFaviconHeight && width == height) return true;
        if (mFaviconWidth == mFaviconHeight && width != height) return false;

        // Do not update favicon if it's already at least as big as the ideal size in both dimens
        if (mFaviconWidth >= mIdealFaviconSize && mFaviconHeight >= mIdealFaviconSize) return false;

        // Update favicon if the new one is larger in one dimen, but not smaller in the other
        return (width > mFaviconWidth && !(height < mFaviconHeight))
                || (!(width < mFaviconWidth) && height > mFaviconHeight);
    }

    @CalledByNative
    protected void onFaviconAvailable(Bitmap icon) {
        if (icon == null) return;
        String url = getUrl();
        boolean pageUrlChanged = !url.equals(mFaviconUrl);
        // This method will be called multiple times if the page has more than one favicon.
        // We are trying to use the |mIdealFaviconSize|x|mIdealFaviconSize| DP icon here, or the
        // first one larger than that received. Bitmap.createScaledBitmap will return the original
        // bitmap if it is already |mIdealFaviconSize|x|mIdealFaviconSize| DP.
        if (pageUrlChanged || isBetterFavicon(icon.getWidth(), icon.getHeight())) {
            mFavicon = Bitmap.createScaledBitmap(icon, mIdealFaviconSize, mIdealFaviconSize, true);
            mFaviconWidth = icon.getWidth();
            mFaviconHeight = icon.getHeight();
            mFaviconUrl = url;
        }

        for (TabObserver observer : mObservers) observer.onFaviconUpdated(this, icon);
    }

    /**
     * Checks if this tab is currently presented in the context of custom tabs. Tabs can be moved
     * between different activities so the returned value might change over the lifetime of the tab.
     * @return true if this is currently a custom tab.
     */
    @CalledByNative
    public boolean isCurrentlyACustomTab() {
        ChromeActivity activity = getActivity();
        return activity != null && activity.isCustomTab();
    }

    /**
     * Called when the navigation entry containing the history item changed,
     * for example because of a scroll offset or form field change.
     */
    @CalledByNative
    private void onNavEntryChanged() {
        mIsTabStateDirty = true;
    }

    /**
     * Called when navigation entries were removed.
     */
    void notifyNavigationEntriesDeleted() {
        mIsTabStateDirty = true;
        for (TabObserver observer : mObservers) observer.onNavigationEntriesDeleted(this);
    }

    /**
     * @return The native pointer representing the native side of this {@link Tab} object.
     */
    @CalledByNative
    private long getNativePtr() {
        return mNativeTabAndroid;
    }

    private static Rect getEstimatedContentSize(Context context) {
        return ExternalPrerenderHandler.estimateContentSize(context, false);
    }

    /** This is currently called when committing a pre-rendered page. */
    @VisibleForTesting
    public void swapWebContents(
            WebContents webContents, boolean didStartLoad, boolean didFinishLoad) {
        int originalWidth = 0;
        int originalHeight = 0;
        if (mContentView != null && mWebContents != null) {
            originalWidth = mContentView.getWidth();
            originalHeight = mContentView.getHeight();
            mWebContents.onHide();
        }

        Rect bounds = new Rect();
        if (originalWidth == 0 && originalHeight == 0) {
            bounds = getEstimatedContentSize(getApplicationContext());
            originalWidth = bounds.right - bounds.left;
            originalHeight = bounds.bottom - bounds.top;
        }

        destroyWebContents(false /* do not delete native web contents */);
        NativePage previousNativePage = mNativePage;
        mNativePage = null;

        // Size of the new content is zero at this point. Set the view size in advance
        // so that next onShow() call won't send a resize message with zero size
        // to the renderer process. This prevents the size fluttering that may confuse
        // Blink and break rendered result (see http://crbug.com/340987).
        webContents.setSize(originalWidth, originalHeight);

        if (!bounds.isEmpty()) {
            nativeOnPhysicalBackingSizeChanged(
                    mNativeTabAndroid, webContents, bounds.right, bounds.bottom);
        }
        webContents.onShow();
        initWebContents(webContents);

        destroyNativePageInternal(previousNativePage);
        for (TabObserver observer : mObservers) {
            observer.onWebContentsSwapped(this, didStartLoad, didFinishLoad);
        }
    }

    @CalledByNative
    private void clearNativePtr() {
        assert mNativeTabAndroid != 0;
        mNativeTabAndroid = 0;
    }

    @CalledByNative
    private void setNativePtr(long nativePtr) {
        assert mNativeTabAndroid == 0;
        mNativeTabAndroid = nativePtr;
    }

    /**
     * @return Whether the TabState representing this Tab has been updated.
     */
    public boolean isTabStateDirty() {
        return mIsTabStateDirty;
    }

    /**
     * Set whether the TabState representing this Tab has been updated.
     * @param isDirty Whether the Tab's state has changed.
     */
    public void setIsTabStateDirty(boolean isDirty) {
        mIsTabStateDirty = isDirty;
    }

    /**
     * @return Whether there are pending {@link LoadUrlParams} associated with the tab.  This
     *         indicates the tab was created for lazy load.
     */
    public boolean hasPendingLoadParams() {
        return mPendingLoadParams != null;
    }

    /**
     * @return Parameters that should be used for a lazily loaded Tab.  May be null.
     */
    private LoadUrlParams getPendingLoadParams() {
        return mPendingLoadParams;
    }

    /**
     * @param params Parameters that should be used for a lazily loaded Tab.
     */
    private void setPendingLoadParams(LoadUrlParams params) {
        mPendingLoadParams = params;
        mUrl = params.getUrl();
    }

    /**
     * @see #setAppAssociatedWith(String) for more information.
     * TODO(aurimas): investigate reducing the visibility of this method after TabModel refactoring.
     *
     * @return The id of the application associated with that tab (null if not
     *         associated with an app).
     */
    public String getAppAssociatedWith() {
        return mAppAssociatedWith;
    }

    /**
     * Associates this tab with the external app with the specified id. Once a Tab is associated
     * with an app, it is reused when a new page is opened from that app (unless the user typed in
     * the location bar or in the page, in which case the tab is dissociated from any app)
     * TODO(aurimas): investigate reducing the visibility of this method after TabModel refactoring.
     *
     * @param appId The ID of application associated with the tab.
     */
    public void setAppAssociatedWith(String appId) {
        mAppAssociatedWith = appId;
    }

    /**
     * @return See {@link #mTimestampMillis}.
     */
    long getTimestampMillis() {
        return mTimestampMillis;
    }

    /**
     * Restores a tab either frozen or from state.
     * TODO(aurimas): investigate reducing the visibility of this method after TabModel refactoring.
     */
    public void createHistoricalTab() {
        if (!isFrozen()) {
            nativeCreateHistoricalTab(mNativeTabAndroid);
        } else if (mFrozenContentsState != null) {
            mFrozenContentsState.createHistoricalTab();
        }
    }

    /**
     * Delete navigation entries from frozen state matching the predicate.
     * @param predicate Handle for a deletion predicate interpreted by native code.
     *                  Only valid during this call frame.
     */
    @CalledByNative
    private void deleteNavigationEntriesFromFrozenState(long predicate) {
        if (mFrozenContentsState == null) return;
        WebContentsState newState = mFrozenContentsState.deleteNavigationEntries(predicate);
        if (newState != null) {
            mFrozenContentsState = newState;
            notifyNavigationEntriesDeleted();
        }
    }

    /**
     * @return The reason the Tab was launched.
     */
    public @TabLaunchType int getLaunchType() {
        return mLaunchType;
    }

    /**
     * @return The reason the Tab was launched.
     */
    public @Nullable @TabLaunchType Integer getLaunchTypeAtInitialTabCreation() {
        return mLaunchTypeAtCreation;
    }

    /**
     * @return true iff the tab doesn't hold a live page. This happens before initialize() and when
     * the tab holds frozen WebContents state that is yet to be inflated.
     */
    @VisibleForTesting
    public boolean isFrozen() {
        return !isNativePage() && getWebContents() == null;
    }

    /**
     * @return An instance of a {@link FullscreenManager}.
     */
    public FullscreenManager getFullscreenManager() {
        return mFullscreenManager;
    }

    /**
     * Enters fullscreen mode. If enabling fullscreen while the tab is not interactable, fullscreen
     * will be delayed until the tab is interactable.
     * @param options Options to adjust fullscreen mode.
     */
    public void enterFullscreenMode(FullscreenOptions options) {
        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) {
            observers.next().onEnterFullscreenMode(this, options);
        }
    }

    /**
     * Exits fullscreen mode. If enabling fullscreen while the tab is not interactable, fullscreen
     * will be delayed until the tab is interactable.
     */
    public void exitFullscreenMode() {
        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) {
            observers.next().onExitFullscreenMode(this);
        }
    }

    /**
     * Push state about whether or not the browser controls can show or hide to the renderer.
     */
    public void updateFullscreenEnabledState() {
        if (isFrozen()) return;

        int constraints = getBrowserControlsStateConstraints();

        updateBrowserControlsState(constraints, BrowserControlsState.BOTH,
                constraints != BrowserControlsState.HIDDEN);

        if (mWebContents != null) {
            GestureListenerManager gestureManager =
                    GestureListenerManager.fromWebContents(mWebContents);
            if (gestureManager != null && mFullscreenManager != null) {
                gestureManager.updateMultiTouchZoomSupport(
                        !mFullscreenManager.getPersistentFullscreenMode());
            }
        }
    }

    /**
     * Updates the browser controls state for this tab.  As these values are set at the renderer
     * level, there is potential for this impacting other tabs that might share the same
     * process.
     *
     * @param constraints The constraints that determine whether the controls can be shown
     *                    or hidden at all.
     * @param current The desired current state for the controls.  Pass
     *                {@link BrowserControlsState#BOTH} to preserve the current position.
     * @param animate Whether the controls should animate to the specified ending condition or
     *                should jump immediately.
     */
    protected void updateBrowserControlsState(@BrowserControlsState int constraints,
            @BrowserControlsState int current, boolean animate) {
        if (mNativeTabAndroid == 0) return;
        nativeUpdateBrowserControlsState(mNativeTabAndroid, constraints, current, animate);

        if (constraints == mBrowserConstrolsConstraints) return;
        mBrowserConstrolsConstraints = constraints;
        for (TabObserver observer : mObservers) {
            observer.onBrowserControlsConstraintsUpdated(this, constraints);
        }
    }

    /**
     * Updates the browser controls state for this tab.  As these values are set at the renderer
     * level, there is potential for this impacting other tabs that might share the same
     * process.
     *
     * @param current The desired current state for the controls.  Pass
     *                {@link BrowserControlsState#BOTH} to preserve the current position.
     * @param animate Whether the controls should animate to the specified ending condition or
     *                should jump immediately.
     */
    public void updateBrowserControlsState(int current, boolean animate) {
        int constraints = getBrowserControlsStateConstraints();
        // Do nothing if current and constraints conflict to avoid error in
        // renderer.
        if ((constraints == BrowserControlsState.HIDDEN && current == BrowserControlsState.SHOWN)
                || (constraints == BrowserControlsState.SHOWN
                           && current == BrowserControlsState.HIDDEN)) {
            return;
        }
        updateBrowserControlsState(getBrowserControlsStateConstraints(), current, animate);
    }

    /**
     * @return Whether hiding browser controls is enabled or not.
     */
    private boolean canAutoHideBrowserControls() {
        return mBrowserControlsVisibilityDelegate.canAutoHideBrowserControls();
    }

    /**
     * Performs any subclass-specific tasks when the Tab crashes.
     */
    void handleTabCrash() {
        mIsLoading = false;

        RewindableIterator<TabObserver> observers = getTabObservers();
        while (observers.hasNext()) observers.next().onCrash(this);
        mIsBeingRestored = false;
    }

    /**
     * @return Whether showing browser controls is enabled or not.
     */
    public boolean canShowBrowserControls() {
        return mBrowserControlsVisibilityDelegate.canShowBrowserControls();
    }

    /**
     * @return The current visibility constraints for the display of browser controls.
     *         {@link BrowserControlsState} defines the valid return options.
     */
    @BrowserControlsState
    public int getBrowserControlsStateConstraints() {
        int constraints = BrowserControlsState.BOTH;
        if (!canShowBrowserControls()) {
            constraints = BrowserControlsState.HIDDEN;
        } else if (!canAutoHideBrowserControls()) {
            constraints = BrowserControlsState.SHOWN;
        }
        return constraints;
    }

    public void setTopControlsHeight(int height, boolean controlsResizeView) {
        mTopControlsHeight = height;
        mControlsResizeView = controlsResizeView;
    }

    public void setBottomControlsHeight(int height) {
        mBottomControlsHeight = height;
    }

    int getTopControlsHeight() {
        return mTopControlsHeight;
    }

    int getBottomControlsHeight() {
        return mBottomControlsHeight;
    }

    boolean controlsResizeView() {
        return mControlsResizeView;
    }

    /**
     * @param manager The fullscreen manager that should be notified of changes to this tab (if
     *                set to null, no more updates will come from this tab).
     */
    public void setFullscreenManager(FullscreenManager manager) {
        mFullscreenManager = manager;
    }

    /**
     * Add a new navigation entry for the current URL and page title.
     */
    void pushNativePageStateToNavigationEntry() {
        assert mNativeTabAndroid != 0 && getNativePage() != null;
        nativeSetActiveNavigationEntryTitleForUrl(mNativeTabAndroid, getNativePage().getUrl(),
                getNativePage().getTitle());
    }

    @Override
    public void onChildViewRemoved(View parent, View child) {
        FullscreenManager fullscreenManager = getFullscreenManager();
        if (fullscreenManager != null) {
            fullscreenManager.updateContentViewChildrenState();
        }
    }

    @Override
    public void onChildViewAdded(View parent, View child) {
        FullscreenManager fullscreenManager = getFullscreenManager();
        if (fullscreenManager != null) {
            fullscreenManager.updateContentViewChildrenState();
        }
    }

    @Override
    public void onSystemUiVisibilityChange(int visibility) {
        FullscreenManager fullscreenManager = getFullscreenManager();
        if (fullscreenManager != null) {
            fullscreenManager.onContentViewSystemUiVisibilityChange(visibility);
        }
    }

    /**
     * @return The ID of the bookmark associated with the current URL, or
     *         {@link #INVALID_BOOKMARK_ID} if no such bookmark exists.
     */
    public long getBookmarkId() {
        return isFrozen() ? INVALID_BOOKMARK_ID : nativeGetBookmarkId(mNativeTabAndroid, false);
    }

    /**
     * Same as getBookmarkId() but never returns ids for managed bookmarks, or any other bookmarks
     * that can't be edited by the user.
     */
    public long getUserBookmarkId() {
        return isFrozen() ? INVALID_BOOKMARK_ID : nativeGetBookmarkId(mNativeTabAndroid, true);
    }

    /**
     * @return Original url of the tab, which is the original url from DOMDistiller.
     */
    public String getOriginalUrl() {
        return DomDistillerUrlUtils.getOriginalUrlFromDistillerUrl(getUrl());
    }

    /**
     * Request that this tab receive focus. Currently, this function requests focus for the main
     * View (usually a ContentView).
     */
    public void requestFocus() {
        View view = getView();
        if (view != null) view.requestFocus();
    }

    @CalledByNative
    protected void openNewTab(String url, String initiatorOrigin, String extraHeaders,
            ResourceRequestBody postData, int disposition, boolean hasParent,
            boolean isRendererInitiated) {
        if (isClosing()) return;

        boolean incognito = isIncognito();
        @TabLaunchType
        int tabLaunchType = TabLaunchType.FROM_LONGPRESS_FOREGROUND;
        Tab parentTab = hasParent ? this : null;

        switch (disposition) {
            case WindowOpenDisposition.NEW_WINDOW: // fall through
            case WindowOpenDisposition.NEW_FOREGROUND_TAB:
                break;
            case WindowOpenDisposition.NEW_POPUP: // fall through
            case WindowOpenDisposition.NEW_BACKGROUND_TAB:
                tabLaunchType = TabLaunchType.FROM_LONGPRESS_BACKGROUND;
                break;
            case WindowOpenDisposition.OFF_THE_RECORD:
                assert incognito;
                incognito = true;
                break;
            default:
                assert false;
        }

        // If shouldIgnoreNewTab returns true, the intent is handled by another
        // activity. As a result, don't launch a new tab to open the URL. If TabModelSelector
        // is not accessible, then we can't open a new tab.
        if (shouldIgnoreNewTab(url, incognito) || getTabModelSelector() == null) return;

        LoadUrlParams loadUrlParams = new LoadUrlParams(url);
        loadUrlParams.setInitiatorOrigin(initiatorOrigin);
        loadUrlParams.setVerbatimHeaders(extraHeaders);
        loadUrlParams.setPostData(postData);
        loadUrlParams.setIsRendererInitiated(isRendererInitiated);
        getTabModelSelector().openNewTab(
                loadUrlParams, tabLaunchType, parentTab, incognito);
    }

    /**
     * @return True if the Tab should block the creation of new tabs via {@link #openNewTab}.
     */
    private boolean shouldIgnoreNewTab(String url, boolean incognito) {
        InterceptNavigationDelegateImpl delegate = getInterceptNavigationDelegate();
        return delegate != null && delegate.shouldIgnoreNewTab(url, incognito);
    }

    /**
     * See {@link #mInterceptNavigationDelegate}.
     */
    public InterceptNavigationDelegateImpl getInterceptNavigationDelegate() {
        return mInterceptNavigationDelegate;
    }

    @VisibleForTesting
    public AuthenticatorNavigationInterceptor getAuthenticatorHelper() {
        return getInterceptNavigationDelegate().getAuthenticatorNavigationInterceptor();
    }

    /**
     * See {@link #mInterceptNavigationDelegate}.
     */
    public void setInterceptNavigationDelegate(InterceptNavigationDelegateImpl delegate) {
        mInterceptNavigationDelegate = delegate;
        nativeSetInterceptNavigationDelegate(mNativeTabAndroid, delegate);
    }

    /**
     * @return the AppBannerManager.
     */
    public AppBannerManager getAppBannerManager() {
        return AppBannerManager.getAppBannerManagerForWebContents(getWebContents());
    }

    @VisibleForTesting
    public boolean hasPrerenderedUrl(String url) {
        return nativeHasPrerenderedUrl(mNativeTabAndroid, url);
    }

    @VisibleForTesting
    public int getSystemWindowInsetBottom() {
        ChromeActivity activity = getActivity();
        if (activity != null && activity.getInsetObserverView() != null) {
            return activity.getInsetObserverView().getSystemWindowInsetsBottom();
        }
        return 0;
    }

    /**
     * Sets the Intent that can be fired to restart the Activity of this Tab's parent.
     * Should only be called if the Tab was launched via a different Activity.
     */
    public void setParentIntent(Intent parentIntent) {
        mParentIntent = parentIntent;
    }

    /**
     * @return Intent that can be fired to restart the parent Activity.
     */
    protected Intent getParentIntent() {
        return mParentIntent;
    }

    /**
     * Creates a new, "frozen" tab from a saved state. This can be used for background tabs restored
     * on cold start that should be loaded when switched to. initialize() needs to be called
     * afterwards to complete the second level initialization.
     */
    public static Tab createFrozenTabFromState(
            int id, boolean incognito, WindowAndroid nativeWindow, int parentId, TabState state) {
        assert state != null;
        return new Tab(id, parentId, incognito, nativeWindow, TabLaunchType.FROM_RESTORE,
                TabCreationState.FROZEN_ON_RESTORE, state);
    }

    /**
     * Update whether or not the current native tab and/or web contents are
     * currently visible (from an accessibility perspective), or whether
     * they're obscured by another view.
     */
    public void updateAccessibilityVisibility() {
        View view = getView();
        if (view != null) {
            int importantForAccessibility = isObscuredByAnotherViewForAccessibility()
                    ? View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS
                    : View.IMPORTANT_FOR_ACCESSIBILITY_YES;
            if (view.getImportantForAccessibility() != importantForAccessibility) {
                view.setImportantForAccessibility(importantForAccessibility);
                view.sendAccessibilityEvent(
                        AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);
            }
        }

        WebContentsAccessibility wcax = getWebContentsAccessibility(getWebContents());
        if (wcax != null) {
            boolean isWebContentObscured =
                    isObscuredByAnotherViewForAccessibility() || SadTab.isShowing(this);
            wcax.setObscuredByAnotherView(isWebContentObscured);
        }
    }

    private boolean isObscuredByAnotherViewForAccessibility() {
        ChromeActivity activity = getActivity();
        return activity != null && activity.isViewObscuringAllTabs();
    }

    /**
     * Creates a new tab to be loaded lazily. This can be used for tabs opened in the background
     * that should be loaded when switched to. initialize() needs to be called afterwards to
     * complete the second level initialization.
     */
    public static Tab createTabForLazyLoad(boolean incognito, WindowAndroid nativeWindow,
            @TabLaunchType int type, int parentId, LoadUrlParams loadUrlParams) {
        Tab tab = new Tab(INVALID_TAB_ID, parentId, incognito, nativeWindow, type,
                TabCreationState.FROZEN_FOR_LAZY_LOAD, null);
        tab.setPendingLoadParams(loadUrlParams);
        return tab;
    }

    /**
     * Creates a fresh tab. initialize() needs to be called afterwards to complete the second level
     * initialization.
     * @param initiallyHidden true iff the tab being created is initially in background
     */
    public static Tab createLiveTab(int id, boolean incognito, WindowAndroid nativeWindow,
            @TabLaunchType int type, int parentId, boolean initiallyHidden) {
        return new Tab(id, parentId, incognito, nativeWindow, type,
                initiallyHidden ? TabCreationState.LIVE_IN_BACKGROUND
                                : TabCreationState.LIVE_IN_FOREGROUND,
                null);
    }

    /**
     * Creates an instance of a {@link Tab} that is fully detached from any activity.
     * Also performs general tab initialization as well as detached specifics.
     *
     * The current application context must allow the creation of a WindowAndroid.
     *
     * @return The newly created and initialized tab.
     */
    public static Tab createDetached(TabDelegateFactory delegateFactory) {
        Context context = ContextUtils.getApplicationContext();
        WindowAndroid windowAndroid = new WindowAndroid(context);
        Tab tab = new Tab(INVALID_TAB_ID, INVALID_TAB_ID, false, windowAndroid,
                TabLaunchType.FROM_SPECULATIVE_BACKGROUND_CREATION, null, null);
        tab.initialize(null, null, delegateFactory, true, false);

        // Resize the webContent to avoid expensive post load resize when attaching the tab.
        Rect bounds = getEstimatedContentSize(context);
        int width = bounds.right - bounds.left;
        int height = bounds.bottom - bounds.top;
        tab.getWebContents().setSize(width, height);

        tab.detach();
        return tab;
    }

    /**
     * @return Intent that tells Chrome to bring an Activity for a particular Tab back to the
     *         foreground, or null if this isn't possible.
     */
    @Nullable
    public static Intent createBringTabToFrontIntent(int tabId) {
        // Iterate through all {@link CustomTab}s and check whether the given tabId belongs to a
        // {@link CustomTab}. If so, return null as the client app's task cannot be foregrounded.
        for (Activity activity : ApplicationStatus.getRunningActivities()) {
            if (activity instanceof CustomTabActivity
                    && ((CustomTabActivity) activity).getActivityTab() != null
                    && tabId == ((CustomTabActivity) activity).getActivityTab().getId()) {
                return null;
            }
        }

        Context context = ContextUtils.getApplicationContext();
        Intent intent = new Intent(context, ChromeLauncherActivity.class);
        intent.putExtra(Browser.EXTRA_APPLICATION_ID, context.getPackageName());
        intent.putExtra(TabOpenType.BRING_TAB_TO_FRONT_STRING, tabId);
        return intent;
    }

    void handleRendererResponsiveStateChanged(boolean isResponsive) {
        mIsRendererUnresponsive = !isResponsive;
        for (TabObserver observer : mObservers) {
            observer.onRendererResponsiveStateChanged(this, isResponsive);
        }
    }

    /**
     * @return Whether the renderer is currently unresponsive.
     */
    protected boolean isRendererUnresponsive() {
        return mIsRendererUnresponsive;
    }

    /**
     * Set whether closing this Tab should return the user to the app that spawned Chrome.
     */
    public void setIsAllowedToReturnToExternalApp(boolean state) {
        mIsAllowedToReturnToExternalApp = state;
    }

    /**
     * @return Whether closing this Tab should return the user to the app that spawned Chrome.
     */
    public boolean isAllowedToReturnToExternalApp() {
        return mIsAllowedToReturnToExternalApp;
    }

    /**
     * @return Whether or not the tab was opened by an app other than Chrome.
     */
    public boolean isCreatedForExternalApp() {
        String packageName = ContextUtils.getApplicationContext().getPackageName();
        return getLaunchType() == TabLaunchType.FROM_EXTERNAL_APP
                && !TextUtils.equals(getAppAssociatedWith(), packageName);
    }

    /**
     * Set the Webapp manifest scope, which is used to allow frames within the scope to autoplay
     * media unmuted.
     */
    public void setWebappManifestScope(String scope) {
        nativeSetWebappManifestScope(mNativeTabAndroid, scope);
    }

    /**
     * Configures web preferences for enabling Picture-in-Picture.
     * @param enabled Whether Picture-in-Picture should be enabled.
     */
    public void setPictureInPictureEnabled(boolean enabled) {
        if (mNativeTabAndroid == 0) return;
        nativeSetPictureInPictureEnabled(mNativeTabAndroid, enabled);
    }

    /**
     * Configures web preferences for viewing downloaded media.
     * @param enabled Whether embedded media experience should be enabled.
     */
    public void enableEmbeddedMediaExperience(boolean enabled) {
        if (mNativeTabAndroid == 0) return;
        nativeEnableEmbeddedMediaExperience(mNativeTabAndroid, enabled);
    }

    /**
     * Handle browser controls when a tab modal dialog is shown.
     * @param isShowing Whether a tab modal dialog is showing.
     */
    public void onTabModalDialogStateChanged(boolean isShowing) {
        mIsShowingTabModalDialog = isShowing;
    }

    /**
     * @return Whether input events from the renderer are ignored on the browser side.
     */
    public boolean areRendererInputEventsIgnored() {
        return nativeAreRendererInputEventsIgnored(mNativeTabAndroid);
    }

    /**
     * @return The publisher URL if the current page is hosted on a trusted CDN, or null otherwise.
     */
    public @Nullable String getTrustedCdnPublisherUrl() {
        ChromeActivity activity = getActivity();
        if (activity == null) return null;
        if (!activity.canShowTrustedCdnPublisherUrl()) return null;
        if (getSecurityLevel() == ConnectionSecurityLevel.DANGEROUS) return null;
        return mTrustedCdnPublisherUrl;
    }

    @CalledByNative
    private void setTrustedCdnPublisherUrl(@Nullable String url) {
        mTrustedCdnPublisherUrl = url;
    }

    private native void nativeInit();
    private native void nativeDestroy(long nativeTabAndroid);
    private native void nativeInitWebContents(long nativeTabAndroid, boolean incognito,
            boolean isBackgroundTab, WebContents webContents, int parentTabId,
            TabWebContentsDelegateAndroid delegate, ContextMenuPopulator contextMenuPopulator);
    private native void nativeUpdateDelegates(long nativeTabAndroid,
            TabWebContentsDelegateAndroid delegate, ContextMenuPopulator contextMenuPopulator);
    private native void nativeDestroyWebContents(long nativeTabAndroid, boolean deleteNative);
    private native void nativeOnPhysicalBackingSizeChanged(
            long nativeTabAndroid, WebContents webContents, int width, int height);
    private native Profile nativeGetProfileAndroid(long nativeTabAndroid);
    private native int nativeLoadUrl(long nativeTabAndroid, String url, String initiatorOrigin,
            String extraHeaders, ResourceRequestBody postData, int transition, String referrerUrl,
            int referrerPolicy, boolean isRendererInitiated, boolean shoulReplaceCurrentEntry,
            boolean hasUserGesture, boolean shouldClearHistoryList, long inputStartTimestamp,
            long intentReceivedTimestamp);
    private native void nativeSetActiveNavigationEntryTitleForUrl(long nativeTabAndroid, String url,
            String title);
    private native Bitmap nativeGetFavicon(long nativeTabAndroid);
    private native void nativeCreateHistoricalTab(long nativeTabAndroid);
    private native void nativeUpdateBrowserControlsState(
            long nativeTabAndroid, int constraints, int current, boolean animate);
    private native void nativeLoadOriginalImage(long nativeTabAndroid);
    private native long nativeGetBookmarkId(long nativeTabAndroid, boolean onlyEditable);
    private native void nativeSetInterceptNavigationDelegate(long nativeTabAndroid,
            InterceptNavigationDelegate delegate);
    private native void nativeAttachToTabContentManager(long nativeTabAndroid,
            TabContentManager tabContentManager);
    private native void nativeClearThumbnailPlaceholder(long nativeTabAndroid);
    private native boolean nativeHasPrerenderedUrl(long nativeTabAndroid, String url);
    private native void nativeSetWebappManifestScope(long nativeTabAndroid, String scope);
    private native void nativeSetPictureInPictureEnabled(long nativeTabAndroid, boolean enabled);
    private native void nativeEnableEmbeddedMediaExperience(long nativeTabAndroid, boolean enabled);
    private native void nativeAttachDetachedTab(long nativeTabAndroid);
    private native boolean nativeAreRendererInputEventsIgnored(long nativeTabAndroid);
}