Updates to VCMDecodedFrameCallback, VideoReceiver and a few related classes/tests.

webrtc/video/video_stream_decoder.cc

 /*
  *  Copyright (c) 2012 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 43 matching lines @@
 
   VCMDecodeErrorMode decode_error_mode = enable_nack ? kNoErrors : kWithErrors;
   video_receiver_->SetVideoProtection(video_protection, true);
   video_receiver_->SetDecodeErrorMode(decode_error_mode);
   VCMPacketRequestCallback* packet_request_callback =
       enable_nack ? vcm_packet_request_callback : nullptr;
   video_receiver_->RegisterPacketRequestCallback(packet_request_callback);
 }
 
 VideoStreamDecoder::~VideoStreamDecoder() {
+  // Note: There's an assumption at this point that the decoder thread is
+  // *not* running. If it was, then there could be a race for each of these
+  // callbacks.
+
   // Unset all the callback pointers that we set in the ctor.
   video_receiver_->RegisterPacketRequestCallback(nullptr);
   video_receiver_->RegisterDecoderTimingCallback(nullptr);
   video_receiver_->RegisterReceiveStatisticsCallback(nullptr);
   video_receiver_->RegisterFrameTypeCallback(nullptr);
   video_receiver_->RegisterReceiveCallback(nullptr);
 }
 
 // Do not acquire the lock of |video_receiver_| in this function. Decode
 // callback won't necessarily be called from the decoding thread. The decoding
@@ skipping 53 matching lines @@
 
 void VideoStreamDecoder::OnCompleteFrame(bool is_keyframe, size_t size_bytes) {}
 
 void VideoStreamDecoder::OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) {
   video_receiver_->SetReceiveChannelParameters(max_rtt_ms);
 
   rtc::CritScope lock(&crit_);
   last_rtt_ms_ = avg_rtt_ms;
 }
 }  // namespace webrtc