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 667 matching lines @@
   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;
   uint32_t frames_encoded;
+  rtc::Optional<uint64_t> qp_sum;
 };
 
 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_