Fix double-deletion of VR Shell when exiting webVR in onPause.

device/vr/android/gvr/gvr_device_provider.cc

Index: device/vr/android/gvr/gvr_device_provider.cc
diff --git a/device/vr/android/gvr/gvr_device_provider.cc b/device/vr/android/gvr/gvr_device_provider.cc
index cf94fb2d5228869c8cb40c50568a19dd4ca68944..c484376ca86eb1d750eda5fed87c9455af288da6 100644
--- a/device/vr/android/gvr/gvr_device_provider.cc
+++ b/device/vr/android/gvr/gvr_device_provider.cc
@@ -69,6 +69,10 @@ bool GvrDeviceProvider::RequestPresent() {
 // VR presentation exit requested by the API.
 void GvrDeviceProvider::ExitPresent() {
   SwitchToNonPresentingDelegate();
+  // If we're presenting currently stop.
+  GvrDelegateProvider* delegate_provider = GvrDelegateProvider::GetInstance();
+  if (delegate_provider)
+    delegate_provider->ExitWebVRPresent();
 }
 
 void GvrDeviceProvider::OnGvrDelegateReady(
@@ -111,9 +115,6 @@ void GvrDeviceProvider::SwitchToNonPresentingDelegate() {
   // Remove GVR gamepad polling.
   GamepadDataFetcherManager::GetInstance()->RemoveSourceFactory(
       GAMEPAD_SOURCE_GVR);
-
-  // If we're presenting currently stop.
-  delegate_provider->ExitWebVRPresent();
 }
 
 }  // namespace device