[chromedriver] Fix 3 bugs about web view, window handle and target window.

Main change is the interface of chrome.h

BUG=chromedriver:241, chromedriver:248, chromedriver:254
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/12978003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@190537 0039d316-1c4b-4281-b951-d872f2087c98
11 files changed