[cc] Forward BeginFrameAcks through DirectCFS and CFSSupport.

cc/test/fake_compositor_frame_sink_client.cc

Index: cc/test/fake_compositor_frame_sink_client.cc
diff --git a/cc/test/fake_compositor_frame_sink_client.cc b/cc/test/fake_compositor_frame_sink_client.cc
index 4e7ba1293ffa3cd4212a879f1959e888fdb43c9b..59963ab5cebe9d7c6fd6dea78ff7346fbcca427e 100644
--- a/cc/test/fake_compositor_frame_sink_client.cc
+++ b/cc/test/fake_compositor_frame_sink_client.cc
@@ -7,6 +7,11 @@
 
 namespace cc {
 
+void FakeCompositorFrameSinkClient::SetBeginFrameSource(
+    BeginFrameSource* source) {
+  begin_frame_source_ = source;
+}
+
 void FakeCompositorFrameSinkClient::DidReceiveCompositorFrameAck() {
   ack_count_++;
 }