Movable support for VideoReceiveStream::Config and avoid copies

webrtc/video_receive_stream.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 58 matching lines @@
     int sync_offset_ms = std::numeric_limits<int>::max();
 
     uint32_t ssrc = 0;
     std::string c_name;
     StreamDataCounters rtp_stats;
     RtcpPacketTypeCounter rtcp_packet_type_counts;
     RtcpStatistics rtcp_stats;
   };
 
   struct Config {
+   private:
+    // Access to the copy constructor is private to force use of the Copy()
+    // method for those exceptional cases where we do use it.
+    Config(const Config&) = default;
+
+   public:
     Config() = delete;
+    Config(Config&&) = default;
     explicit Config(Transport* rtcp_send_transport)
         : rtcp_send_transport(rtcp_send_transport) {}
 
+    Config& operator=(Config&&) = default;
+    Config& operator=(const Config&) = delete;
+
+    // Mostly used by tests.  Avoid creating copies if you can.
+    Config Copy() const { return Config(*this); }
+
     std::string ToString() const;
 
     // Decoders for every payload that we can receive.
     std::vector<Decoder> decoders;
 
     // Receive-stream specific RTP settings.
     struct Rtp {
       std::string ToString() const;
 
       // Synchronization source (stream identifier) to be received.
@@ skipping 92 matching lines @@
   // TODO(pbos): Add info on currently-received codec to Stats.
   virtual Stats GetStats() const = 0;
 
  protected:
   virtual ~VideoReceiveStream() {}
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_RECEIVE_STREAM_H_