Introduce XGetImage() for GrabWindowSnapshot() in ChromeOS.

BUG=119492
TEST=manually done

Review URL: https://chromiumcodereview.appspot.com/10386124

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137556 0039d316-1c4b-4281-b951-d872f2087c98
void RootWindow::OnLayerAnimationScheduled(
    ui::LayerAnimationSequence* animation) {
}

void RootWindow::OnLayerAnimationScheduled(
    ui::LayerAnimationSequence* animation) {
}
