Movable support for VideoReceiveStream::Config and avoid copies

webrtc/video/receive_statistics_proxy.h

 /*
  *  Copyright (c) 2013 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 19 matching lines @@
 class Clock;
 class ViECodec;
 class ViEDecoderObserver;
 struct CodecSpecificInfo;
 
 class ReceiveStatisticsProxy : public VCMReceiveStatisticsCallback,
                                public RtcpStatisticsCallback,
                                public RtcpPacketTypeCounterObserver,
                                public StreamDataCountersCallback {
  public:
-  ReceiveStatisticsProxy(const VideoReceiveStream::Config& config,
+  ReceiveStatisticsProxy(const VideoReceiveStream::Config* config,
                          Clock* clock);
   virtual ~ReceiveStatisticsProxy();
 
   VideoReceiveStream::Stats GetStats() const;
 
   void OnDecodedFrame();
   void OnSyncOffsetUpdated(int64_t sync_offset_ms);
   void OnRenderedFrame(int width, int height);
   void OnIncomingPayloadType(int payload_type);
   void OnDecoderImplementationName(const char* implementation_name);
@@ skipping 38 matching lines @@
     int sum;
     int num_samples;
   };
   struct QpCounters {
     SampleCounter vp8;
   };
 
   void UpdateHistograms() EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   Clock* const clock_;
-  const VideoReceiveStream::Config config_;
+  // Ownership of this object lies with the owner of the ReceiveStatisticsProxy
+  // instance.  Lifetime is guaranteed to outlive |this|.
+  // TODO(tommi): In practice the config_ reference is only used for accessing
+  // config_.rtp.fec.ulpfec_payload_type.  Instead of holding a pointer back,
+  // we could just store the value of ulpfec_payload_type and change the
+  // ReceiveStatisticsProxy() ctor to accept a const& of Config (since we'll
+  // then no longer store a pointer to the object).
+  const VideoReceiveStream::Config& config_;
 
   rtc::CriticalSection crit_;
   VideoReceiveStream::Stats stats_ GUARDED_BY(crit_);
   RateStatistics decode_fps_estimator_ GUARDED_BY(crit_);
   RateStatistics renders_fps_estimator_ GUARDED_BY(crit_);
   rtc::RateTracker render_fps_tracker_ GUARDED_BY(crit_);
   rtc::RateTracker render_pixel_tracker_ GUARDED_BY(crit_);
   SampleCounter render_width_counter_ GUARDED_BY(crit_);
   SampleCounter render_height_counter_ GUARDED_BY(crit_);
   SampleCounter sync_offset_counter_ GUARDED_BY(crit_);
   SampleCounter decode_time_counter_ GUARDED_BY(crit_);
   SampleCounter jitter_buffer_delay_counter_ GUARDED_BY(crit_);
   SampleCounter target_delay_counter_ GUARDED_BY(crit_);
   SampleCounter current_delay_counter_ GUARDED_BY(crit_);
   SampleCounter delay_counter_ GUARDED_BY(crit_);
   ReportBlockStats report_block_stats_ GUARDED_BY(crit_);
   QpCounters qp_counters_;  // Only accessed on the decoding thread.
   std::map<uint32_t, StreamDataCounters> rtx_stats_ GUARDED_BY(crit_);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_VIDEO_RECEIVE_STATISTICS_PROXY_H_