Standardize usage of virtual/override/final in media/

media/cdm/player_tracker_impl.h

Index: media/cdm/player_tracker_impl.h
diff --git a/media/cdm/player_tracker_impl.h b/media/cdm/player_tracker_impl.h
index 768f5a682893c8af20f560c23bf7a30879e5b414..6d4cee3b879eec66ecaf868ae6f83096be20b18a 100644
--- a/media/cdm/player_tracker_impl.h
+++ b/media/cdm/player_tracker_impl.h
@@ -21,12 +21,12 @@ namespace media {
 class MEDIA_EXPORT PlayerTrackerImpl : public PlayerTracker {
  public:
   PlayerTrackerImpl();
-  virtual ~PlayerTrackerImpl();
+  ~PlayerTrackerImpl() override;
 
   // PlayerTracker implementation.
-  virtual int RegisterPlayer(const base::Closure& new_key_cb,
-                             const base::Closure& cdm_unset_cb) override;
-  virtual void UnregisterPlayer(int registration_id) override;
+  int RegisterPlayer(const base::Closure& new_key_cb,
+                     const base::Closure& cdm_unset_cb) override;
+  void UnregisterPlayer(int registration_id) override;
 
   // Helpers methods to fire registered callbacks.
   void NotifyNewKey();