Modify the parameter type of PeerConnectionObserver callback OnAddTrack.

webrtc/api/peerconnectioninterface_unittest.cc

 /*
  *  Copyright 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 544 matching lines @@
 
   void OnIceCandidatesRemoved(
       const std::vector<cricket::Candidate>& candidates) override {
     callback_triggered_ = true;
   }
 
   void OnIceConnectionReceivingChange(bool receiving) override {
     callback_triggered_ = true;
   }
 
-  void OnAddTrack(rtc::scoped_refptr<webrtc::RtpReceiverInterface> receiver,
-                  std::vector<rtc::scoped_refptr<webrtc::MediaStreamInterface>>
-                      streams) override {
+  void OnAddTrack(
+      rtc::scoped_refptr<webrtc::RtpReceiverInterface> receiver,
+      const std::vector<rtc::scoped_refptr<webrtc::MediaStreamInterface>>&
+          streams) override {
     EXPECT_TRUE(receiver != nullptr);
     num_added_tracks_++;
     last_added_track_label_ = receiver->id();
   }
 
   // Returns the label of the last added stream.
   // Empty string if no stream have been added.
   std::string GetLastAddedStreamLabel() {
     if (last_added_stream_.get())
       return last_added_stream_->label();
@@ skipping 2403 matching lines @@
   FakeConstraints updated_answer_c;
   answer_c.SetMandatoryReceiveAudio(false);
   answer_c.SetMandatoryReceiveVideo(false);
 
   cricket::MediaSessionOptions updated_answer_options;
   EXPECT_TRUE(
       ParseConstraintsForAnswer(&updated_answer_c, &updated_answer_options));
   EXPECT_TRUE(updated_answer_options.has_audio());
   EXPECT_TRUE(updated_answer_options.has_video());
 }