Add support of vrdisplayconnect and vrdisplaydisconnect event

device/vr/vr_client_dispatcher.h

Index: device/vr/vr_client_dispatcher.h
diff --git a/device/vr/vr_client_dispatcher.h b/device/vr/vr_client_dispatcher.h
index 7be327708daa54058e2b5a21dccd4762a5fc443c..692769a5124079a50a08ce9f873da5c876fd1169 100644
--- a/device/vr/vr_client_dispatcher.h
+++ b/device/vr/vr_client_dispatcher.h
@@ -9,9 +9,13 @@
 
 namespace device {
 
+class VRDevice;
+
 class VRClientDispatcher {
  public:
   virtual void OnDeviceChanged(VRDisplayPtr device) = 0;
+  virtual void OnDeviceConnectionStatusChanged(VRDevice* device,
+                                               bool is_connected) = 0;
 };
 
 }  // namespace device