Pause drawing webvr when the App button is pressed

chrome/browser/android/vr_shell/ui_interface.h

 // Copyright 2016 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_ANDROID_VR_SHELL_UI_INTERFACE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_INTERFACE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 31 matching lines @@
   void SetWebVRSecureOrigin(bool secure);
   void SetLoading(bool loading);
   void SetLoadProgress(double progress);
   void InitTabList();
   void AppendToTabList(bool incognito, int id, const base::string16& title);
   void FlushTabList();
   void UpdateTab(bool incognito, int id, const std::string& title);
   void RemoveTab(bool incognito, int id);
   void SetURL(const GURL& url);
   void HandleAppButtonGesturePerformed(Direction direction);
-  void HandleAppButtonClicked();
   void SetHistoryButtonsEnabled(bool can_go_back, bool can_go_forward);
 
  private:
   Mode mode_;
   bool fullscreen_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(UiInterface);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_INTERFACE_H_