Standardize usage of virtual/override/final in content/

content/child/threaded_data_provider.cc

Index: content/child/threaded_data_provider.cc
diff --git a/content/child/threaded_data_provider.cc b/content/child/threaded_data_provider.cc
index 25bbcf898f1f89b25e5ef6fe9bd77b3b80e8d654..f7a6c66f1dd5fd4a2249d428d9d436904a3f6fc9 100644
--- a/content/child/threaded_data_provider.cc
+++ b/content/child/threaded_data_provider.cc
@@ -31,11 +31,11 @@ class DataProviderMessageFilter : public IPC::MessageFilter {
       int request_id);
 
   // IPC::ChannelProxy::MessageFilter
-  virtual void OnFilterAdded(IPC::Sender* sender) override final;
-  virtual bool OnMessageReceived(const IPC::Message& message) override final;
+  void OnFilterAdded(IPC::Sender* sender) final;
+  bool OnMessageReceived(const IPC::Message& message) final;
 
  private:
-  virtual ~DataProviderMessageFilter() { }
+  ~DataProviderMessageFilter() override {}
 
   void OnReceivedData(int request_id, int data_offset, int data_length,
                       int encoded_data_length);