VRDisplay inherits from EventTarget

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

 // 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.
 
 #include "modules/vr/VRDisplay.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/FrameRequestCallback.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/ScriptedAnimationController.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
+#include "modules/EventTargetModules.h"
 #include "modules/vr/NavigatorVR.h"
 #include "modules/vr/VRController.h"
 #include "modules/vr/VRDisplayCapabilities.h"
 #include "modules/vr/VREyeParameters.h"
 #include "modules/vr/VRFrameData.h"
 #include "modules/vr/VRLayer.h"
 #include "modules/vr/VRPose.h"
 #include "modules/vr/VRStageParameters.h"
 #include "modules/webgl/WebGLRenderingContextBase.h"
 #include "platform/Histogram.h"
@@ skipping 29 matching lines @@
   }
 
   Member<VRDisplay> m_vrDisplay;
 };
 
 }  // namespace
 
 VRDisplay::VRDisplay(NavigatorVR* navigatorVR,
                      device::mojom::blink::VRDisplayPtr display,
                      device::mojom::blink::VRDisplayClientRequest request)
-    : m_navigatorVR(navigatorVR),
+    : ActiveScriptWrappable(this),
+      ActiveDOMObject(navigatorVR->document()),
+      m_navigatorVR(navigatorVR),
       m_isConnected(false),
       m_isPresenting(false),
       m_canUpdateFramePose(true),
       m_capabilities(new VRDisplayCapabilities()),
       m_eyeParametersLeft(new VREyeParameters()),
       m_eyeParametersRight(new VREyeParameters()),
       m_depthNear(0.01),
       m_depthFar(10000.0),
       m_fullscreenCheckTimer(this, &VRDisplay::onFullscreenCheck),
       m_contextGL(nullptr),
@@ skipping 583 matching lines @@
   if (!m_scriptedAnimationController)
     m_scriptedAnimationController = ScriptedAnimationController::create(doc);
 
   return *m_scriptedAnimationController;
 }
 
 void VRDisplay::dispose() {
   m_binding.Close();
 }
 
+ExecutionContext* VRDisplay::getExecutionContext() const {
+  return ContextLifecycleObserver::getExecutionContext();

[bajones, 2016/11/29 00:15:44]

Seems more common in objects that derive from ActiveDOMObject to use

ActiveDOMObject::getExecutionContext();

See:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/animation...

+}
+
+const AtomicString& VRDisplay::interfaceName() const {
+  return EventTargetNames::VRDisplay;
+}
+
+void VRDisplay::suspend() {
+  // TODO(xing.xu): Implement suspend.
+}
+
+void VRDisplay::resume() {
+  // TODO(xing.xu): Implement resume.
+}
+
+void VRDisplay::contextDestroyed() {
+  // TODO(xing.xu): Implement destory. Such as forceExitPresent().

[bajones, 2016/11/29 00:15:44]

Minor typo here ("destory" -> "destroy") but rather than fix that I think we
should simply call forceExitPresent(). here as suggested in the comment.

[haraken, 2016/11/29 01:43:28]

If you're not sure what to do in contextDestroyed, I'd prefer deferring adding
ActiveDOMObject to a later CL.

[mlamouri (slow - plz ping), 2016/12/01 10:10:06]

+1, it sounds that you dan't have a need for the object to be an
ActiveDOMOObject yet.

+}
+
+bool VRDisplay::hasPendingActivity() const {
+  // Prevent V8 from garbage collecting the wrapper object if there are
+  // event listeners attached to it.
+  return hasEventListeners();
+}
+
 DEFINE_TRACE(VRDisplay) {
+  EventTargetWithInlineData::trace(visitor);
+  ActiveDOMObject::trace(visitor);
   visitor->trace(m_navigatorVR);
   visitor->trace(m_capabilities);
   visitor->trace(m_stageParameters);
   visitor->trace(m_eyeParametersLeft);
   visitor->trace(m_eyeParametersRight);
   visitor->trace(m_layer);
   visitor->trace(m_renderingContext);
   visitor->trace(m_scriptedAnimationController);
 }
 
 }  // namespace blink