Add support of vrdisplayconnect and vrdisplaydisconnect event

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 fd54be19b18fd25a5f2d2177b92c21e704801732..f3fca4998052440614d5bc8e9cc17f3b9c0c1d02 100644
--- a/device/vr/android/gvr/gvr_device_provider.cc
+++ b/device/vr/android/gvr/gvr_device_provider.cc
@@ -58,6 +58,12 @@ void GvrDeviceProvider::Initialize() {
   }
 }
 
+void GvrDeviceProvider::SetClient(VRClientDispatcher* client) {
+  if (!vr_device_)
+    return;
+  vr_device_->SetClient(client);
+}
+
 void GvrDeviceProvider::OnGvrApiInitialized(gvr::GvrApi* gvr_api) {
   if (!vr_device_)
     vr_device_.reset(new GvrDevice(this, gvr_api));
@@ -69,4 +75,9 @@ void GvrDeviceProvider::OnGvrApiShutdown() {
   // Nothing to do here just yet. Eventually want to shut down the VRDevice
 }
 
+void GvrDeviceProvider::PollEvents() {
+  if (vr_device_)
+    vr_device_->PollEvents();
+}
+
 }  // namespace device