VRDisplay inherits from EventTarget

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

Index: third_party/WebKit/Source/modules/vr/VRDisplay.cpp
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
index a266f43d9b194bc884955d27c1c2187d10041e79..be1f2f1a479fbd4b5c3086ebf6627fac67bca976 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -13,6 +13,7 @@
 #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"
@@ -62,7 +63,9 @@ class VRDisplayFrameRequestCallback : public FrameRequestCallback {
 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),
@@ -666,7 +669,35 @@ 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);