Add support of vrdisplayconnect and vrdisplaydisconnect event

third_party/WebKit/Source/modules/vr/VRDisplay.h

 // Copyright 2016 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 VRDisplay_h
 #define VRDisplay_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/Document.h"
 #include "core/dom/FrameRequestCallback.h"
@@ skipping 61 matching lines @@
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     friend class VRController;
 
     VRDisplay(NavigatorVR*);
 
     void update(const device::blink::VRDisplayPtr&);
 
+    void disconnected();
+
     VRController* controller();
 
 private:
     // TaskObserver implementation.
     void didProcessTask() override;
     void willProcessTask() override { }
 
     void onFullscreenCheck(TimerBase*);
 
     Member<NavigatorVR> m_navigatorVR;
@@ skipping 11 matching lines @@
     VRLayer m_layer;
 
     Timer<VRDisplay> m_fullscreenCheckTimer;
 };
 
 using VRDisplayVector = HeapVector<Member<VRDisplay>>;
 
 } // namespace blink
 
 #endif // VRDisplay_h