Enforce marking "override" for functions overriding Blink in components/.

components/message_port/web_message_port_channel_impl.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_MESSAGE_PORT_WEB_MESSAGE_PORT_CHANNEL_IMPL_H_
 #define COMPONENTS_MESSAGE_PORT_WEB_MESSAGE_PORT_CHANNEL_IMPL_H_
 
 #include "base/basictypes.h"
 #include "mojo/message_pump/handle_watcher.h"
 #include "third_party/WebKit/public/platform/WebMessagePortChannel.h"
 #include "third_party/mojo/src/mojo/public/cpp/system/message_pipe.h"
 
 namespace message_port {
 
 class WebMessagePortChannelImpl : public blink::WebMessagePortChannel {
  public:
   static void CreatePair(
       blink::WebMessagePortChannel** channel1,
       blink::WebMessagePortChannel** channel2);
 
  private:
   explicit WebMessagePortChannelImpl(mojo::ScopedMessagePipeHandle pipe);
   virtual ~WebMessagePortChannelImpl();
 
   // blink::WebMessagePortChannel implementation.
-  virtual void setClient(blink::WebMessagePortChannelClient* client);
-  virtual void destroy();
-  virtual void postMessage(const blink::WebString& message,
-                           blink::WebMessagePortChannelArray* channels);
-  virtual bool tryGetMessage(blink::WebString* message,
-                             blink::WebMessagePortChannelArray& channels);
+  void setClient(blink::WebMessagePortChannelClient* client) override;
+  void destroy() override;
+  void postMessage(const blink::WebString& message,
+                   blink::WebMessagePortChannelArray* channels) override;
+  bool tryGetMessage(blink::WebString* message,
+                     blink::WebMessagePortChannelArray& channels) override;
 
   void WaitForNextMessage();
   void OnMessageAvailable(MojoResult result);
 
   blink::WebMessagePortChannelClient* client_;
   mojo::ScopedMessagePipeHandle pipe_;
   mojo::common::HandleWatcher handle_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMessagePortChannelImpl);
 };
 
 }  // namespace message_port
 
 #endif  // COMPONENTS_MESSAGE_PORT_WEB_MESSAGE_PORT_CHANNEL_IMPL_H_