Enable -Winconsistent-missing-override flag.

webrtc/media/engine/fakewebrtcvoiceengine.h

Index: webrtc/media/engine/fakewebrtcvoiceengine.h
diff --git a/webrtc/media/engine/fakewebrtcvoiceengine.h b/webrtc/media/engine/fakewebrtcvoiceengine.h
index 33629160bc116d1139c6f9dc59e43b9c6bac1921..eb59c5a7c735d9ac3d7b61d8042b1dafe4f389ec 100644
--- a/webrtc/media/engine/fakewebrtcvoiceengine.h
+++ b/webrtc/media/engine/fakewebrtcvoiceengine.h
@@ -310,7 +310,7 @@ class FakeWebRtcVoiceEngine
     channels_[channel]->associate_send_channel = accociate_send_channel;
     return 0;
   }
-  webrtc::RtcEventLog* GetEventLog() { return nullptr; }
+  webrtc::RtcEventLog* GetEventLog() override { return nullptr; }
 
   // webrtc::VoECodec
   WEBRTC_STUB(NumOfCodecs, ());
@@ -461,11 +461,11 @@ class FakeWebRtcVoiceEngine
   WEBRTC_STUB(SetPlayoutSampleRate, (unsigned int samples_per_sec));
   WEBRTC_STUB_CONST(PlayoutSampleRate, (unsigned int* samples_per_sec));
   WEBRTC_STUB(EnableBuiltInAEC, (bool enable));
-  virtual bool BuiltInAECIsAvailable() const { return false; }
+  bool BuiltInAECIsAvailable() const override { return false; }
   WEBRTC_STUB(EnableBuiltInAGC, (bool enable));
-  virtual bool BuiltInAGCIsAvailable() const { return false; }
+  bool BuiltInAGCIsAvailable() const override { return false; }
   WEBRTC_STUB(EnableBuiltInNS, (bool enable));
-  virtual bool BuiltInNSIsAvailable() const { return false; }
+  bool BuiltInNSIsAvailable() const override { return false; }
 
   // webrtc::VoENetwork
   WEBRTC_FUNC(RegisterExternalTransport, (int channel,
@@ -673,17 +673,17 @@ class FakeWebRtcVoiceEngine
                                              int reportingThreshold,
                                              int penaltyDecay,
                                              int typeEventDelay));
-  int EnableHighPassFilter(bool enable) {
+  int EnableHighPassFilter(bool enable) override {
     highpass_filter_enabled_ = enable;
     return 0;
   }
-  bool IsHighPassFilterEnabled() {
+  bool IsHighPassFilterEnabled() override {
     return highpass_filter_enabled_;
   }
-  bool IsStereoChannelSwappingEnabled() {
+  bool IsStereoChannelSwappingEnabled() override {
     return stereo_swapping_enabled_;
   }
-  void EnableStereoChannelSwapping(bool enable) {
+  void EnableStereoChannelSwapping(bool enable) override {
     stereo_swapping_enabled_ = enable;
   }
   int GetNetEqCapacity() const {