Replace the only use of media::MockStatisticsCB with a bound method.

media/base/mock_filters.h

 // Copyright (c) 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 MEDIA_BASE_MOCK_FILTERS_H_
 #define MEDIA_BASE_MOCK_FILTERS_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 222 matching lines @@
   MOCK_METHOD2(DecryptAndDecodeVideo,
                void(const scoped_refptr<media::DecoderBuffer>& encrypted,
                     const VideoDecodeCB& video_decode_cb));
   MOCK_METHOD1(ResetDecoder, void(StreamType stream_type));
   MOCK_METHOD1(DeinitializeDecoder, void(StreamType stream_type));
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockDecryptor);
 };
 
-// Helper mock statistics callback.
-class MockStatisticsCB {
- public:
-  MockStatisticsCB();
-  ~MockStatisticsCB();
-
-  MOCK_METHOD1(OnStatistics, void(const media::PipelineStatistics& statistics));
-};
-
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FILTERS_H_