Fix exiting WebVR via Android UI not fully exiting fullscreen.

device/vr/android/gvr/gvr_device_provider.h

Index: device/vr/android/gvr/gvr_device_provider.h
diff --git a/device/vr/android/gvr/gvr_device_provider.h b/device/vr/android/gvr/gvr_device_provider.h
index 02f77583ffe40b6b46863e8073ab45194a29c8a0..5c561f4cde7254aad114befede161e4e8b62b070 100644
--- a/device/vr/android/gvr/gvr_device_provider.h
+++ b/device/vr/android/gvr/gvr_device_provider.h
@@ -15,6 +15,7 @@
 
 namespace device {
 
+class GvrDelegateProvider;
 class GvrDelegate;
 class GvrDevice;
 class VRServiceImpl;
@@ -39,6 +40,8 @@ class DEVICE_VR_EXPORT GvrDeviceProvider : public VRDeviceProvider {
   void GvrDelegateReady(GvrDelegate* delegate);
   void GvrDelegateRemoved();
 
+  void SwitchToNonPresentingDelegate();
+
   std::unique_ptr<GvrDevice> vr_device_;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;