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 53f01abf603e76b75ec81659f2dad0a456024ddd..1eaa9872261c89b93a9219a91e9b51add32f6957 100644
--- a/device/vr/android/gvr/gvr_device_provider.h
+++ b/device/vr/android/gvr/gvr_device_provider.h
@@ -16,6 +16,7 @@
 
 namespace device {
 
+class GvrDelegateProvider;
 class GvrDelegate;
 class GvrDevice;
 class VRServiceImpl;
@@ -38,6 +39,8 @@ class DEVICE_VR_EXPORT GvrDeviceProvider : public VRDeviceProvider {
   void OnDisplayFocus();
 
  private:
+  void SwitchToNonPresentingDelegate();
+
   std::unique_ptr<GvrDevice> vr_device_;
 
   base::WeakPtrFactory<GvrDeviceProvider> weak_ptr_factory_;