Fix WebVR getDevices promise not resolving when VR Services are not compatible.

device/vr/android/gvr/gvr_device_provider.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "device/vr/android/gvr/gvr_device_provider.h"
 
 #include <jni.h>
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_android.h"
@@ skipping 16 matching lines @@
   device::GvrDelegateProvider* delegate_provider =
       device::GvrDelegateProvider::GetInstance();
   if (delegate_provider) {
     delegate_provider->ExitWebVRPresent();
     delegate_provider->ClearDeviceProvider();
   }
 }
 
 void GvrDeviceProvider::GetDevices(std::vector<VRDevice*>* devices) {
   Initialize();
-  devices->push_back(vr_device_.get());
+  if (initialized_)
+    devices->push_back(vr_device_.get());
 }
 
 void GvrDeviceProvider::Initialize() {
   // TODO(mthiesse): Clean up how we connect the GvrDelegateProvider to the
   // GvrDeviceProvider so we don't have to call this function multiple times.
   // Ideally the DelegateProvider would always be available, and GetInstance()
   // would create it.
   if (initialized_)
     return;
   device::GvrDelegateProvider* delegate_provider =
@@ skipping 29 matching lines @@
   Initialize();
   device::GvrDelegateProvider* delegate_provider =
       device::GvrDelegateProvider::GetInstance();
   if (!delegate_provider)
     return;
 
   delegate_provider->SetListeningForActivate(listening);
 }
 
 }  // namespace device