Initialize cc::VideoFrameProviderClientImpl::active_video_layer_ to NULL.

cc/test/fake_video_frame_provider.h

 // 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.
 
 #ifndef CC_TEST_FAKE_VIDEO_FRAME_PROVIDER_H_
 #define CC_TEST_FAKE_VIDEO_FRAME_PROVIDER_H_
 
 #include "cc/layers/video_frame_provider.h"
 #include "media/base/video_frame.h"
 
 namespace cc {
 
 // Fake video frame provider that always provides the same VideoFrame.
 class FakeVideoFrameProvider : public VideoFrameProvider {
  public:
   FakeVideoFrameProvider();
   virtual ~FakeVideoFrameProvider();
 
   virtual void SetVideoFrameProviderClient(Client* client) OVERRIDE;
   virtual scoped_refptr<media::VideoFrame> GetCurrentFrame() OVERRIDE;
   virtual void PutCurrentFrame(const scoped_refptr<media::VideoFrame>&)
       OVERRIDE {}
 
+  Client* client() { return client_; }
+
   void set_frame(const scoped_refptr<media::VideoFrame>& frame) {
     frame_ = frame;
   }
 
  private:
   scoped_refptr<media::VideoFrame> frame_;
   Client* client_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_VIDEO_FRAME_PROVIDER_H_