Standardize usage of virtual/override/final in content/

content/common/message_router.h

Index: content/common/message_router.h
diff --git a/content/common/message_router.h b/content/common/message_router.h
index ac89929c6848946c34d4c5012061d498523efb7c..a842f8eb899ee60c15d3e59d633a6df96e26527b 100644
--- a/content/common/message_router.h
+++ b/content/common/message_router.h
@@ -32,13 +32,13 @@ namespace content {
 class MessageRouter : public IPC::Listener, public IPC::Sender {
  public:
   MessageRouter();
-  virtual ~MessageRouter();
+  ~MessageRouter() override;
 
   // Implemented by subclasses to handle control messages
   virtual bool OnControlMessageReceived(const IPC::Message& msg);
 
   // IPC::Listener implementation:
-  virtual bool OnMessageReceived(const IPC::Message& msg) override;
+  bool OnMessageReceived(const IPC::Message& msg) override;
 
   // Like OnMessageReceived, except it only handles routed messages.  Returns
   // true if the message was dispatched, or false if there was no listener for
@@ -46,7 +46,7 @@ class MessageRouter : public IPC::Listener, public IPC::Sender {
   virtual bool RouteMessage(const IPC::Message& msg);
 
   // IPC::Sender implementation:
-  virtual bool Send(IPC::Message* msg) override;
+  bool Send(IPC::Message* msg) override;
 
   // Called to add a listener for a particular message routing ID.
   // Returns true if succeeded.