Add event listening function to openvr device

device/vr/openvr/openvr_device.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DEVICE_VR_OPENVR_DEVICE_H
 #define DEVICE_VR_OPENVR_DEVICE_H
 
 #include "base/macros.h"
 #include "base/threading/simple_thread.h"
 #include "device/vr/vr_device.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace vr {
 class IVRSystem;
 }  // namespace vr
 
 namespace device {
 
 class OpenVRDevice : public VRDevice {
  public:
+  enum VREvent { CONNECTED = 0, DISCONNECTED = 1, CHANGED = 2 };
+
   OpenVRDevice();
   ~OpenVRDevice() override;
 
   // VRDevice
   void CreateVRDisplayInfo(
       const base::Callback<void(mojom::VRDisplayInfoPtr)>& on_created) override;
 
   void RequestPresent(mojom::VRSubmitFrameClientPtr submit_client,
                       const base::Callback<void(bool)>& callback) override;
   void SetSecureOrigin(bool secure_origin) override;
   void ExitPresent() override;
 
   void SubmitFrame(int16_t frame_index,
                    const gpu::MailboxHolder& mailbox) override;
   void UpdateLayerBounds(int16_t frame_index,
                          mojom::VRLayerBoundsPtr left_bounds,
                          mojom::VRLayerBoundsPtr right_bounds,
                          int16_t source_width,
                          int16_t source_height) override;
   void GetVRVSyncProvider(mojom::VRVSyncProviderRequest request) override;
 
+  void OnPollingEvent(OpenVRDevice::VREvent event);
+
  private:
   class OpenVRRenderLoop : public base::SimpleThread,
                            device::mojom::VRVSyncProvider {
    public:
     OpenVRRenderLoop(vr::IVRSystem* vr);
 
+    void RegistPollingEventCallback(
+        const base::Callback<void(OpenVRDevice::VREvent)>& onPollingVREvent);
+
+    void UnregistPollingEventCallback();
+
     void Bind(mojom::VRVSyncProviderRequest request);
 
     mojom::VRPosePtr getPose();
 
+    vr::IVRSystem* GetVRSystem();
+
+    // OpenVR need invoke pollNextEvent to query system event.
+    void PollEvents();
+
    private:
     void Run() override;
 
     void GetVSync(const device::mojom::VRVSyncProvider::GetVSyncCallback&
                       callback) override;
 
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+    base::Callback<void(OpenVRDevice::VREvent)> on_polling_event_;
     vr::IVRSystem* vr_system_;
     mojo::Binding<device::mojom::VRVSyncProvider> binding_;
   };
 
   std::unique_ptr<OpenVRRenderLoop>
       render_loop_;  // TODO (BillOrr): This should not be a unique_ptr because
                      // the render_loop_ binds to VRVSyncProvider requests,
                      // so its lifetime should be tied to the lifetime of that
                      // binding.
 
   mojom::VRSubmitFrameClientPtr submit_client_;
 
+  base::WeakPtrFactory<OpenVRDevice> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(OpenVRDevice);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_VR_OPENVR_DEVICE_H