GitLab

Allow the renderer to subscribe to a vsync notification from the
browser. This change adds the necessary IPC plumbing but does not
actually implement the vsync signal source; this is done with a
separate patch.

BUG=149227

Review URL: https://chromiumcodereview.appspot.com/13068002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195136 0039d316-1c4b-4281-b951-d872f2087c98