Add QP sum stats for received streams.

webrtc/video_decoder.h

 /*
  *  Copyright (c) 2014 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.
  */
 
@@ skipping 22 matching lines @@
   virtual int32_t Decoded(VideoFrame& decodedImage) = 0;
   // Provides an alternative interface that allows the decoder to specify the
   // decode time excluding waiting time for any previous pending frame to
   // return. This is necessary for breaking positive feedback in the delay
   // estimation when the decoder has a single output buffer.
   // TODO(perkj): Remove default implementation when chromium has been updated.
   virtual int32_t Decoded(VideoFrame& decodedImage, int64_t decode_time_ms) {
     // The default implementation ignores custom decode time value.
     return Decoded(decodedImage);
   }
+  virtual int32_t DecodedWithQp(VideoFrame& decodedImage, int qp) = 0;
+  virtual int32_t DecodedWithQp(VideoFrame& decodedImage,
+                                int64_t decode_time_ms,
+                                int qp) = 0;

[hbos, 2017/01/25 11:31:13]

I think there should just be one Decoded function with rtc::Optional<uint64_t>
qp. Is decode_time_ms also optional? (If it is but changing to optional is a
pain it can remain int64_t.)

You can add:
virtual int32_t Decoded(VideoFrame& decoded_image,
                        rtc::Optional<int64_t> decode_time_ms,
                        rtc::Optional<uint64_t> qp) {
  Decoded(decoded_image, decode_time_ms ? *decode_time_ms : -1);
}

And a TODO to remove default implementations / other Decoded versions when
upstream projects have implemented it.

[sakal, 2017/01/25 12:39:34]

I removed the other DecodedWithQp method and renamed the other to Decoded. See
other comment for rtc::Optional discussion.

 
   virtual int32_t ReceivedDecodedReferenceFrame(const uint64_t pictureId) {
     return -1;
   }
 
   virtual int32_t ReceivedDecodedFrame(const uint64_t pictureId) { return -1; }
 };
 
 class VideoDecoder {
  public:
@@ skipping 17 matching lines @@
   // That is, it can not decode infinite number of frames before the decoded
   // frame is consumed.
   virtual bool PrefersLateDecoding() const { return true; }
 
   virtual const char* ImplementationName() const { return "unknown"; }
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_DECODER_H_