Implement WebVR presentation pausing for VR Shell Menu Mode

device/vr/android/gvr/gvr_gamepad_data_fetcher.cc

Index: device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
diff --git a/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
index 17bc49a7a358822c037493cbef2544a44c8ec9dd..219897a60bc8a0a15bbe6f11ccf5b7289bd3cf0d 100644
--- a/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
+++ b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
@@ -28,16 +28,18 @@ void CopyToWebUString(blink::WebUChar* dest,
 
 using namespace blink;
 
-GvrGamepadDataFetcher::Factory::Factory(GvrDelegate* delegate,
-                                        unsigned int display_id)
+GvrGamepadDataFetcher::Factory::Factory(
+    const base::WeakPtr<GvrDelegate>& delegate,
+    unsigned int display_id)
     : delegate_(delegate), display_id_(display_id) {}
 
 GvrGamepadDataFetcher::Factory::~Factory() {}
 
 std::unique_ptr<GamepadDataFetcher>
 GvrGamepadDataFetcher::Factory::CreateDataFetcher() {
-  return std::unique_ptr<GamepadDataFetcher>(
-      new GvrGamepadDataFetcher(delegate_, display_id_));
+  if (!delegate_)
+    return nullptr;
+  return base::MakeUnique<GvrGamepadDataFetcher>(delegate_.get(), display_id_);
 }
 
 GamepadSource GvrGamepadDataFetcher::Factory::source() {