[Android] Provide synchronized input flush with BeginFrame

The BufferedInputRouter relies on periodic flush signals.  Provide hooks for
such flush requests and signals via the RenderWidgetHostView, and wire this
to BeginFrame messages on Android. Expose the functionality behind the
--enable-buffered-input-router flag.

BUG=245499,264869

Review URL: https://codereview.chromium.org/23983036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225387 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225387
Rename VideoCaptureDevice::EventHandler to VideoCaptureDevice::Client.

BUG=

Review URL: https://codereview.chromium.org/24331002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225388 0039d316-1c4b-4281-b951-d872f2087c98
cc: Make tile manager responsible for tile's lifetime.

This patch is somewhat proof-of-concept to make ManageTiles be the only
spot where tiles can be deleted. This allows all function calls between
two ManageTiles calls to assume that the state has not changed.

BUG=

Review URL: https://codereview.chromium.org/24331009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225389 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225389