Pause drawing webvr when the App button is pressed

chrome/browser/android/vr_shell/vr_gl_thread.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_VR_GL_THREAD_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_GL_THREAD_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
+#include "chrome/browser/android/vr_shell/vr_thread_envoy.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr_types.h"
 
 namespace vr_shell {
 
 class UiScene;
 class UiSceneManager;
 class VrShell;
 class VrShellGl;
 
-class VrGLThread : public base::Thread {
+class VrGLThread : public VrThreadEnvoy, public base::Thread {
  public:
   VrGLThread(
       const base::WeakPtr<VrShell>& weak_vr_shell,
       scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner,
       gvr_context* gvr_api,
       bool initially_web_vr,
       bool reprojected_rendering);
 
   ~VrGLThread() override;
+  void PostToMainThread(const base::Closure& task);
   base::WeakPtr<VrShellGl> GetVrShellGl() { return weak_vr_shell_gl_; }
   base::WeakPtr<UiSceneManager> GetSceneManager() {
     return weak_scene_manager_;
   }
 
+  // VrThreadEnvoy implementation.
+  base::WeakPtr<VrShell> GetVrShell() override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetMainThreadTaskRunner()
+      override;
+
  protected:
   void Init() override;
   void CleanUp() override;
 
  private:
   // Created on GL thread.
   std::unique_ptr<UiScene> scene_;
   std::unique_ptr<UiSceneManager> scene_manager_;
   base::WeakPtr<UiSceneManager> weak_scene_manager_;
   std::unique_ptr<VrShellGl> vr_shell_gl_;
   base::WeakPtr<VrShellGl> weak_vr_shell_gl_;
 
   // This state is used for initializing vr_shell_gl_.
   base::WeakPtr<VrShell> weak_vr_shell_;
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
   gvr_context* gvr_api_;
   bool initially_web_vr_;
   bool reprojected_rendering_;
 
+  base::WeakPtrFactory<VrGLThread> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(VrGLThread);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_GL_THREAD_H_