Add OVERRIDE to ipc/.

ipc/ipc_sync_message_filter.h

Index: ipc/ipc_sync_message_filter.h
diff --git a/ipc/ipc_sync_message_filter.h b/ipc/ipc_sync_message_filter.h
index 4b5b55f8234dae183828b474435871f4b0cb08a1..1f0f46d86c72c9f10421b7d2f9113b4a81d830be 100644
--- a/ipc/ipc_sync_message_filter.h
+++ b/ipc/ipc_sync_message_filter.h
@@ -33,13 +33,13 @@ class IPC_EXPORT SyncMessageFilter : public ChannelProxy::MessageFilter,
   virtual ~SyncMessageFilter();
 
   // Message::Sender implementation.
-  virtual bool Send(Message* message);
+  virtual bool Send(Message* message) OVERRIDE;
 
   // ChannelProxy::MessageFilter implementation.
-  virtual void OnFilterAdded(Channel* channel);
-  virtual void OnChannelError();
-  virtual void OnChannelClosing();
-  virtual bool OnMessageReceived(const Message& message);
+  virtual void OnFilterAdded(Channel* channel) OVERRIDE;
+  virtual void OnChannelError() OVERRIDE;
+  virtual void OnChannelClosing() OVERRIDE;
+  virtual bool OnMessageReceived(const Message& message) OVERRIDE;
 
  private:
   void SendOnIOThread(Message* message);