Fix VideoCapturer::OnMessage override

webrtc/media/base/videocapturer.h

Index: webrtc/media/base/videocapturer.h
diff --git a/webrtc/media/base/videocapturer.h b/webrtc/media/base/videocapturer.h
index 0320034cad789b3d00fe591677cdcbf4b42f89dd..543af026c04f25423a79d8d309cd7f35a019acd2 100644
--- a/webrtc/media/base/videocapturer.h
+++ b/webrtc/media/base/videocapturer.h
@@ -289,7 +289,7 @@ class VideoCapturer : public sigslot::has_slots<>,
   void SetCaptureState(CaptureState state);
 
   // Marshals SignalStateChange onto thread_.
-  void OnMessage(rtc::Message* message);
+  void OnMessage(rtc::Message* message) override;
 
   // subclasses override this virtual method to provide a vector of fourccs, in
   // order of preference, that are expected by the media engine.