Enable -Winconsistent-missing-override flag.

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 406 matching lines @@
  public:
   MockPeerConnectionObserver() : remote_streams_(StreamCollection::Create()) {}
   ~MockPeerConnectionObserver() {
   }
   void SetPeerConnectionInterface(PeerConnectionInterface* pc) {
     pc_ = pc;
     if (pc) {
       state_ = pc_->signaling_state();
     }
   }
-  virtual void OnSignalingChange(
-      PeerConnectionInterface::SignalingState new_state) {
+  void OnSignalingChange(
+      PeerConnectionInterface::SignalingState new_state) override {
     EXPECT_EQ(pc_->signaling_state(), new_state);
     state_ = new_state;
   }
   // TODO(bemasc): Remove this once callers transition to OnIceGatheringChange.
   virtual void OnStateChange(StateType state_changed) {
     if (pc_.get() == NULL)
       return;
     switch (state_changed) {
       case kSignalingState:
         // OnSignalingChange and OnStateChange(kSignalingState) should always
@@ skipping 2222 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());
 }