Add stats for average QP per frame for VP8 (for received video streams).

webrtc/modules/video_coding/utility/include/qp_parser.h

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_COMMON_VIDEO_ROTATION_H_
-#define WEBRTC_COMMON_VIDEO_ROTATION_H_
+#ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_
+
+#include "webrtc/modules/video_coding/main/source/encoded_frame.h"
 
 namespace webrtc {
 
-// enum for clockwise rotation.
-enum VideoRotation {
-  kVideoRotation_0 = 0,
-  kVideoRotation_90 = 90,
-  kVideoRotation_180 = 180,
-  kVideoRotation_270 = 270
+class QpParser {
+ public:
+  QpParser() {}
+  ~QpParser() {}
+
+  // Parses an encoded |frame| and extracts the |qp|.
+  // Returns true on success, false otherwise.
+  bool GetQp(const VCMEncodedFrame& frame, int* qp);
 };
 
 }  // namespace webrtc
 
-#endif  // WEBRTC_COMMON_VIDEO_ROTATION_H_
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_QP_PARSER_H_