Pause drawing webvr when the App button is pressed

chrome/browser/android/vr_shell/vr_shell_gl.h

Index: chrome/browser/android/vr_shell/vr_shell_gl.h
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.h b/chrome/browser/android/vr_shell/vr_shell_gl.h
index 277ddfa4ecb87155da930820c7d98284bbdda60c..76fb91b0a189d3ade42c5ed73214c79caae64164 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.h
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.h
@@ -44,6 +44,7 @@ class FPSMeter;
 class MailboxToSurfaceBridge;
 class UiScene;
 class VrController;
+class VrGLThread;
 class VrShell;
 class VrShellRenderer;
 struct UiElement;
@@ -67,8 +68,7 @@ class VrShellGl : public device::mojom::VRVSyncProvider {
     CONTENT,
   };
 
-  VrShellGl(const base::WeakPtr<VrShell>& weak_vr_shell,
-            scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner,
+  VrShellGl(const base::WeakPtr<VrGLThread>& weak_vr_gl_thread,
             gvr_context* gvr_api,
             bool initially_web_vr,
             bool reprojected_rendering,
@@ -225,8 +225,7 @@ class VrShellGl : public device::mojom::VRVSyncProvider {
   mojo::Binding<device::mojom::VRVSyncProvider> binding_;
   device::mojom::VRSubmitFrameClientPtr submit_client_;
 
-  base::WeakPtr<VrShell> weak_vr_shell_;
-  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+  base::WeakPtr<VrGLThread> weak_vr_gl_thread_;
 
   UiScene* scene_ = nullptr;