Force a GuestView's embedder to be focused on TouchStart.
It is currently possible that touching (TouchStart) an element inside a
GuestView may not focus the element because the embedder itself has not
received focus. An example of this is when a <webview> tag is contained
inside a views::WebView. The views::WebView is unable to receive touch
events in order to focus itself, and the BrowserPlugin marks the touch
event as handled so that Aura never generates the GestureTap that
RenderWidgetHostViewAura requires to focus the views::WebView.
This CL adds logic in RenderWidgetHostViewGuest to detect an unfocused
embedder, and to focus it on TouchStart.
BUG=450147
Review URL: https://codereview.chromium.org/1180503002
Cr-Commit-Position: refs/heads/master@{#335569}
4 files changed
