Adding in ffmpeg_common.h into header for definition of CodecID.

media/base/mock_ffmpeg.h

 // Copyright (c) 2009 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_FFMPEG_H_
 #define MEDIA_BASE_MOCK_FFMPEG_H_
 
+// TODO(scherkus): See if we can remove ffmpeg_common from this file.
+#include "media/filters/ffmpeg_common.h"
+
 #include "testing/gmock/include/gmock/gmock.h"
 
-struct AVCodec;
-struct AVCodecContext;
-struct AVFrame;
-struct AVPacket;
-enum CodecID;
-
 namespace media {
 
 class MockFFmpeg {
  public:
   MOCK_METHOD1(AVCodecFindDecoder, AVCodec*(enum CodecID id));
   MOCK_METHOD2(AVCodecOpen, int(AVCodecContext* avctx, AVCodec* codec));
   MOCK_METHOD2(AVCodecThreadInit, int(AVCodecContext* avctx, int threads));
 
   // Setter/getter for the global instance of MockFFmpeg.
   static void set(MockFFmpeg* instance);
   static MockFFmpeg* get();
 
  private:
   static MockFFmpeg* instance_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FFMPEG_H_