cc: Video layers without a frame should not occlude

cc/test/fake_video_frame_provider.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/test/fake_video_frame_provider.h"
 
 namespace cc {
 
 FakeVideoFrameProvider::FakeVideoFrameProvider()
     : frame_(NULL), client_(NULL) {}
 
 FakeVideoFrameProvider::~FakeVideoFrameProvider() {
   if (client_)
     client_->StopUsingProvider();
 }
 
 bool FakeVideoFrameProvider::UpdateCurrentFrame(base::TimeTicks deadline_min,
                                                 base::TimeTicks deadline_max) {
   return false;
 }
 
 void FakeVideoFrameProvider::SetVideoFrameProviderClient(Client* client) {
   client_ = client;
 }
 
+bool FakeVideoFrameProvider::HasCurrentFrame() {
+  return frame_;
+}
+
 scoped_refptr<media::VideoFrame> FakeVideoFrameProvider::GetCurrentFrame() {
   return frame_;
 }
 
 }  // namespace cc