Add event listening function to openvr device

device/vr/openvr/openvr_device.h

Index: device/vr/openvr/openvr_device.h
diff --git a/device/vr/openvr/openvr_device.h b/device/vr/openvr/openvr_device.h
index 7bc96f90b982421daeb388aad3f6c11b1f5b6c10..f4b2d1d7258962f7a5d30acc86b64e78fe9a2f29 100644
--- a/device/vr/openvr/openvr_device.h
+++ b/device/vr/openvr/openvr_device.h
@@ -39,12 +39,19 @@ class OpenVRDevice : public VRDevice {
                          int16_t source_height) override;
   void GetVRVSyncProvider(mojom::VRVSyncProviderRequest request) override;
 
+  void OnPollingEvents();
+
  private:
   class OpenVRRenderLoop : public base::SimpleThread,
                            device::mojom::VRVSyncProvider {
    public:
     OpenVRRenderLoop(vr::IVRSystem* vr);
 
+    void RegisterPollingEventCallback(
+        const base::Callback<void()>& onPollingEvents);
+
+    void UnregisterPollingEventCallback();
+
     void Bind(mojom::VRVSyncProviderRequest request);
 
     mojom::VRPosePtr getPose();
@@ -56,6 +63,7 @@ class OpenVRDevice : public VRDevice {
                       callback) override;
 
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+    base::Callback<void()> on_polling_events_;
     vr::IVRSystem* vr_system_;
     mojo::Binding<device::mojom::VRVSyncProvider> binding_;
   };
@@ -70,6 +78,10 @@ class OpenVRDevice : public VRDevice {
 
   vr::IVRSystem* vr_system_;
 
+  bool is_polling_events_;
+
+  base::WeakPtrFactory<OpenVRDevice> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(OpenVRDevice);
 };