Add support of vrdisplayconnect and vrdisplaydisconnect event

device/vr/vr_device.h

Index: device/vr/vr_device.h
diff --git a/device/vr/vr_device.h b/device/vr/vr_device.h
index 632aec5a5c19498c7897339fe08af51e4c07e008..4d43e086b07b2fb5abfb9feb1406dfc54a10941a 100644
--- a/device/vr/vr_device.h
+++ b/device/vr/vr_device.h
@@ -6,6 +6,7 @@
 #define DEVICE_VR_VR_DEVICE_H
 
 #include "base/macros.h"
+#include "device/vr/vr_client_dispatcher.h"
 #include "device/vr/vr_export.h"
 #include "device/vr/vr_service.mojom.h"
 
@@ -29,14 +30,19 @@ class VRDevice {
   DEVICE_VR_EXPORT virtual ~VRDevice();
 
   DEVICE_VR_EXPORT VRDeviceProvider* provider() const { return provider_; }
+  DEVICE_VR_EXPORT VRClientDispatcher* client() const { return client_; }
   DEVICE_VR_EXPORT unsigned int id() const { return id_; }
 
   virtual VRDisplayPtr GetVRDevice() = 0;
   virtual VRPosePtr GetPose() = 0;
   virtual void ResetPose() = 0;
+  virtual void PollEvents() = 0;

[bajones, 2016/09/06 23:25:46]

As I'm looking through this code it occurs to me that we'll probably only be
firing events like this during PollEvents. For now lets pass the
VRClientDispatcher into this function rather than storing it as a member on the
VRDevice/VRDeviceProvider.

[shaobo.yan, 2016/09/07 02:45:50]

I'll move client_ from VRDevice to VRDeviceProvider to process
connect/disconnect signal.

+
+  void SetClient(VRClientDispatcher* client) { client_ = client; }
 
  private:
   VRDeviceProvider* provider_;
+  VRClientDispatcher* client_;
   unsigned int id_;
 
   static unsigned int next_id_;