Implement qpSum stat for video send ssrc stats.

webrtc/media/base/mediachannel.h

 /*
  *  Copyright (c) 2004 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 648 matching lines @@
         send_frame_width(0),
         send_frame_height(0),
         framerate_input(0),
         framerate_sent(0),
         nominal_bitrate(0),
         preferred_bitrate(0),
         adapt_reason(0),
         adapt_changes(0),
         avg_encode_ms(0),
         encode_usage_percent(0),
-        frames_encoded(0) {}
+        frames_encoded(0),
+        qp_sum(0) {}
 
   std::vector<SsrcGroup> ssrc_groups;
   std::string encoder_implementation_name;
   int packets_cached;
   int firs_rcvd;
   int plis_rcvd;
   int nacks_rcvd;
   int send_frame_width;
   int send_frame_height;
   int framerate_input;
   int framerate_sent;
   int nominal_bitrate;
   int preferred_bitrate;
   int adapt_reason;
   int adapt_changes;
   int avg_encode_ms;
   int encode_usage_percent;
   int frames_encoded;
+  int qp_sum;

[hbos, 2016/10/20 17:08:21]

Should be uint32_t.

What about the decoded case? I think there should be a qp_sum in
VideoReceiverInfo as well.

From spec:
  The sum of the QP values of frames passed. The count
  of frames is in framesDecoded for inbound
  stream stats, and in framesEncoded for
  outbound stream stats.

This only covers the RTCOutboundRTPStreamStats case.

[sakal, 2016/10/21 08:59:43]

I'd prefer to implement it in another CL. It will be considerably more work and
adding this for the encoding case satisfies our immediate use case.

 };
 
 struct VideoReceiverInfo : public MediaReceiverInfo {
   VideoReceiverInfo()
       : packets_concealed(0),
         firs_sent(0),
         plis_sent(0),
         nacks_sent(0),
         frame_width(0),
         frame_height(0),
@@ skipping 437 matching lines @@
   // Signal when the media channel is ready to send the stream. Arguments are:
   //     writable(bool)
   sigslot::signal1<bool> SignalReadyToSend;
   // Signal for notifying that the remote side has closed the DataChannel.
   sigslot::signal1<uint32_t> SignalStreamClosedRemotely;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_MEDIACHANNEL_H_