Standardize usage of virtual/override/final in mojo/

mojo/shell/app_child_process_host.h

 // Copyright 2014 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 MOJO_SHELL_APP_CHILD_PROCESS_HOST_H_
 #define MOJO_SHELL_APP_CHILD_PROCESS_HOST_H_
 
 #include "base/macros.h"
 #include "mojo/shell/app_child_process.mojom.h"
 #include "mojo/shell/child_process_host.h"
 
 namespace mojo {
 
 namespace embedder {
 struct ChannelInfo;
 }
 
 namespace shell {
 
 // A subclass of |ChildProcessHost| to host a |TYPE_APP| child process, which
 // runs a single app (loaded from the file system).
 //
 // Note: After |Start()|, this object must remain alive until the controller
 // client's |AppCompleted()| is called.
 class AppChildProcessHost : public ChildProcessHost,
                             public ChildProcessHost::Delegate {
  public:
   AppChildProcessHost(Context* context,
                       AppChildControllerClient* controller_client);
-  virtual ~AppChildProcessHost();
+  ~AppChildProcessHost() override;
 
   AppChildController* controller() {
     return controller_.get();
   }
 
  private:
   // |ChildProcessHost::Delegate| methods:
-  virtual void WillStart() override;
-  virtual void DidStart(bool success) override;
+  void WillStart() override;
+  void DidStart(bool success) override;
 
   // Callback for |embedder::CreateChannel()|.
   void DidCreateChannel(embedder::ChannelInfo* channel_info);
 
   AppChildControllerClient* const controller_client_;
 
   AppChildControllerPtr controller_;
   embedder::ChannelInfo* channel_info_;
 
   DISALLOW_COPY_AND_ASSIGN(AppChildProcessHost);
 };
 
 }  // namespace shell
 }  // namespace mojo
 
 #endif  // MOJO_SHELL_APP_CHILD_PROCESS_HOST_H_