Remove remote tree host and some related input and metro_driver code

chrome/browser/browser_process_platform_part_aurawin.h

 // Copyright (c) 2013 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 CHROME_BROWSER_BROWSER_PROCESS_PLATFORM_PART_AURAWIN_H_
 #define CHROME_BROWSER_BROWSER_PROCESS_PLATFORM_PART_AURAWIN_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/browser_process_platform_part_base.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
-class ChromeMetroViewerProcessHost;
-
 class BrowserProcessPlatformPart : public BrowserProcessPlatformPartBase,
                                    public content::NotificationObserver {
  public:
   BrowserProcessPlatformPart();
   ~BrowserProcessPlatformPart() override;
 
-  // Invoked when the ASH metro viewer process on Windows 8 exits.
-  void OnMetroViewerProcessTerminated();
-
   // Overridden from BrowserProcessPlatformPartBase:
   void PlatformSpecificCommandLineProcessing(
       const base::CommandLine& command_line) override;
 
   // content::NotificationObserver method:
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
  private:
-  // Hosts the channel for the Windows 8 metro viewer process which runs in
-  // the ASH environment.
-  scoped_ptr<ChromeMetroViewerProcessHost> metro_viewer_process_host_;
-
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserProcessPlatformPart);
 };
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_PLATFORM_PART_AURAWIN_H_