WebVR: move animation state check to deferred task

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/FrameRequestCallback.h"
 #include "core/dom/ScriptedAnimationController.h"
@@ skipping 672 matching lines @@
       EventTypeNames::vrdisplayactivate, true, false, this, reason));
 }
 
 void VRDisplay::OnDeactivate(
     device::mojom::blink::VRDisplayEventReason reason) {
   m_navigatorVR->enqueueVREvent(VRDisplayEvent::create(
       EventTypeNames::vrdisplaydeactivate, true, false, this, reason));
 }
 
 void VRDisplay::processScheduledAnimations(double timestamp) {
+  // Check if we still have a valid context, the animation controller
+  // or document may have disappeared since we scheduled this.
+  Document* doc = this->document();
+  if (!doc || m_displayBlurred || !m_scriptedAnimationController)
+    return;
+
   TRACE_EVENT1("gpu", "VRDisplay::OnVSync", "frame", m_vrFrameId);
 
   AutoReset<bool> animating(&m_inAnimationFrame, true);
   m_pendingRaf = false;
+
   m_scriptedAnimationController->serviceScriptedAnimations(timestamp);
 }
 
 void VRDisplay::OnVSync(device::mojom::blink::VRPosePtr pose,
                         mojo::common::mojom::blink::TimeDeltaPtr time,
                         int16_t frameId,
                         device::mojom::blink::VRVSyncProvider::Status error) {
   switch (error) {
     case device::mojom::blink::VRVSyncProvider::Status::SUCCESS:
       break;
     case device::mojom::blink::VRVSyncProvider::Status::CLOSING:
       return;
   }
   m_pendingVsync = false;
-  Document* doc = this->document();
-  if (!doc || m_displayBlurred || !m_scriptedAnimationController)
-    return;
 
   WTF::TimeDelta timeDelta =
       WTF::TimeDelta::FromMicroseconds(time->microseconds);
   // Ensure a consistent timebase with document rAF.
   if (m_timebase < 0) {
     m_timebase = WTF::monotonicallyIncreasingTime() - timeDelta.InSecondsF();
   }
 
   m_framePose = std::move(pose);
   m_vrFrameId = frameId;
@@ skipping 76 matching lines @@
   visitor->trace(m_stageParameters);
   visitor->trace(m_eyeParametersLeft);
   visitor->trace(m_eyeParametersRight);
   visitor->trace(m_layer);
   visitor->trace(m_renderingContext);
   visitor->trace(m_scriptedAnimationController);
   visitor->trace(m_pendingPresentResolvers);
 }
 
 }  // namespace blink