cc: Video layers without a frame should not occlude

cc/test/fake_video_frame_provider.cc

Index: cc/test/fake_video_frame_provider.cc
diff --git a/cc/test/fake_video_frame_provider.cc b/cc/test/fake_video_frame_provider.cc
index 3f4b40b7612a9e1c3fd38a2274c7876ab553a563..b979b0c95e098646a2d8e5302c33b1c6f76e074a 100644
--- a/cc/test/fake_video_frame_provider.cc
+++ b/cc/test/fake_video_frame_provider.cc
@@ -23,6 +23,10 @@ void FakeVideoFrameProvider::SetVideoFrameProviderClient(Client* client) {
   client_ = client;
 }
 
+bool FakeVideoFrameProvider::HasCurrentFrame() {
+  return frame_;
+}
+
 scoped_refptr<media::VideoFrame> FakeVideoFrameProvider::GetCurrentFrame() {
   return frame_;
 }