[cc] Forward BeginFrameAcks through DirectCFS and CFSSupport.

cc/surfaces/compositor_frame_sink_support.cc

Index: cc/surfaces/compositor_frame_sink_support.cc
diff --git a/cc/surfaces/compositor_frame_sink_support.cc b/cc/surfaces/compositor_frame_sink_support.cc
index 7930d9e7b2eae1db80a48b95b458e4604778fbd7..e6bb39603f9a1503fb3c0a231c38077a4c65c458 100644
--- a/cc/surfaces/compositor_frame_sink_support.cc
+++ b/cc/surfaces/compositor_frame_sink_support.cc
@@ -68,6 +68,11 @@ void CompositorFrameSinkSupport::SetNeedsBeginFrame(bool needs_begin_frame) {
   UpdateNeedsBeginFramesInternal();
 }
 
+void CompositorFrameSinkSupport::DidFinishFrame(const BeginFrameAck& ack) {
+  if (begin_frame_source_)
+    begin_frame_source_->DidFinishFrame(this, ack);
+}
+
 void CompositorFrameSinkSupport::SubmitCompositorFrame(
     const LocalSurfaceId& local_surface_id,
     CompositorFrame frame) {