Standardize usage of virtual/override/final in media/

media/cast/net/rtcp/receiver_rtcp_event_subscriber.h

Index: media/cast/net/rtcp/receiver_rtcp_event_subscriber.h
diff --git a/media/cast/net/rtcp/receiver_rtcp_event_subscriber.h b/media/cast/net/rtcp/receiver_rtcp_event_subscriber.h
index 5a9acb79bc7f5c4dd430f1f4b8288216035ec7e2..c08733ca94d2a49bc455e89b19021aca829bd33b 100644
--- a/media/cast/net/rtcp/receiver_rtcp_event_subscriber.h
+++ b/media/cast/net/rtcp/receiver_rtcp_event_subscriber.h
@@ -37,11 +37,11 @@ class ReceiverRtcpEventSubscriber : public RawEventSubscriber {
   ReceiverRtcpEventSubscriber(const size_t max_size_to_retain,
       EventMediaType type);
 
-  virtual ~ReceiverRtcpEventSubscriber();
+  ~ReceiverRtcpEventSubscriber() override;
 
   // RawEventSubscriber implementation.
-  virtual void OnReceiveFrameEvent(const FrameEvent& frame_event) override;
-  virtual void OnReceivePacketEvent(const PacketEvent& packet_event) override;
+  void OnReceiveFrameEvent(const FrameEvent& frame_event) override;
+  void OnReceivePacketEvent(const PacketEvent& packet_event) override;
 
   // Assigns events collected to |rtcp_events| and clears them from this
   // object.