Add support of vrdisplayconnect and vrdisplaydisconnect event

device/vr/android/gvr/gvr_device_provider.h

 // 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.
 
 #ifndef DEVICE_VR_ANDROID_GVR_DEVICE_PROVIDER_H
 #define DEVICE_VR_ANDROID_GVR_DEVICE_PROVIDER_H
 
 #include <jni.h>
 
 #include <memory>
 
 #include "base/android/jni_android.h"
 #include "base/macros.h"
 #include "device/vr/android/gvr/gvr_api_manager.h"
 #include "device/vr/vr_device.h"
 #include "device/vr/vr_device_provider.h"
 
 namespace device {
 
+class VRClientDispatcher;
+
 class GvrDeviceProvider : public VRDeviceProvider, public GvrApiManagerClient {
  public:
   GvrDeviceProvider();
   ~GvrDeviceProvider() override;
 
   void GetDevices(std::vector<VRDevice*>* devices) override;
   void Initialize() override;
+  void SetClient(VRClientDispatcher* client) override;
 
   // GvrApiManagerClient
   void OnGvrApiInitialized(gvr::GvrApi* gvr_api) override;
   void OnGvrApiShutdown() override;
 
+  void PollEvents() override;
+
  private:
   std::unique_ptr<VRDevice> vr_device_;
   base::android::ScopedJavaGlobalRef<jobject> j_device_;
 
   DISALLOW_COPY_AND_ASSIGN(GvrDeviceProvider);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_VR_ANDROID_GVR_DEVICE_PROVIDER_H