Add support of vrdisplayconnect and vrdisplaydisconnect event

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 d3e3225f7f3f525059e9e31decd3c06667917bc1..da126f3f07087ffa7e7a869357926df5ac27da1e 100644
--- a/device/vr/android/gvr/gvr_device_provider.h
+++ b/device/vr/android/gvr/gvr_device_provider.h
@@ -17,6 +17,8 @@
 
 namespace device {
 
+class VRClientDispatcher;
+
 class GvrDeviceProvider : public VRDeviceProvider, public GvrApiManagerClient {
  public:
   GvrDeviceProvider();
@@ -24,11 +26,14 @@ class GvrDeviceProvider : public VRDeviceProvider, public GvrApiManagerClient {
 
   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_;