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

components/message_port/web_message_port_channel_impl.h

Index: components/message_port/web_message_port_channel_impl.h
diff --git a/components/message_port/web_message_port_channel_impl.h b/components/message_port/web_message_port_channel_impl.h
index 12d6c286ee991370a257f2b23bdb5a8247009a51..493631f94e01bc51f9bedc1d553171babc4a4343 100644
--- a/components/message_port/web_message_port_channel_impl.h
+++ b/components/message_port/web_message_port_channel_impl.h
@@ -23,12 +23,12 @@ class WebMessagePortChannelImpl : public blink::WebMessagePortChannel {
   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);