Pause drawing webvr when the App button is pressed

chrome/browser/android/vr_shell/ui_scene.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_SCENE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_SCENE_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 50 matching lines @@
   std::vector<const UiElement*> GetWorldElements() const;
   std::vector<const UiElement*> GetHeadLockedElements() const;
   bool HasVisibleHeadLockedElements() const;
 
   void SetBackgroundColor(const vr::Colorf& color);
   const vr::Colorf& GetBackgroundColor() const;
   void SetBackgroundDistance(float distance);
   float GetBackgroundDistance() const;
 
   bool GetWebVrRenderingEnabled() const;
+  void SetWebVrRenderingEnabled(bool enabled);
 
   void OnGLInitialized();
 
  private:
   void ApplyRecursiveTransforms(UiElement* element);
 
   std::vector<std::unique_ptr<UiElement>> ui_elements_;
   UiElement* content_element_ = nullptr;
   vr::Colorf background_color_ = {0.1f, 0.1f, 0.1f, 1.0f};
   float background_distance_ = 10.0f;
   bool webvr_rendering_enabled_ = true;
   bool gl_initialized_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(UiScene);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_SCENE_H_