WebVR: avoid race conditions for partially-initialized display

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"
@@ skipping 57 matching lines @@
 };
 
 }  // namespace
 
 VRDisplay::VRDisplay(NavigatorVR* navigatorVR,
                      device::mojom::blink::VRDisplayPtr display,
                      device::mojom::blink::VRDisplayClientRequest request)
     : m_navigatorVR(navigatorVR),
       m_isConnected(false),
       m_isPresenting(false),
+      m_isValidDeviceForPresenting(true),
       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),
       m_animationCallbackRequested(false),
       m_inAnimationFrame(false),
@@ skipping 13 matching lines @@
   m_displayName = display->displayName;
   m_isConnected = true;
 
   m_capabilities->setHasOrientation(display->capabilities->hasOrientation);
   m_capabilities->setHasPosition(display->capabilities->hasPosition);
   m_capabilities->setHasExternalDisplay(
       display->capabilities->hasExternalDisplay);
   m_capabilities->setCanPresent(display->capabilities->canPresent);
   m_capabilities->setMaxLayers(display->capabilities->canPresent ? 1 : 0);
 
+  // Ignore non presenting delegate
+  bool isValid = display->leftEye->renderWidth > 0;
+  bool needOnPresentChange = false;
+  if (m_isPresenting && isValid && !m_isValidDeviceForPresenting) {
+    needOnPresentChange = true;
+  }
+  m_isValidDeviceForPresenting = isValid;
   m_eyeParametersLeft->update(display->leftEye);
   m_eyeParametersRight->update(display->rightEye);
 
   if (!display->stageParameters.is_null()) {
     if (!m_stageParameters)
       m_stageParameters = new VRStageParameters();
     m_stageParameters->update(display->stageParameters);
   } else {
     m_stageParameters = nullptr;
   }
+
+  if (needOnPresentChange) {
+    OnPresentChange();
+  }
 }
 
 void VRDisplay::disconnected() {
   if (m_isConnected)
     m_isConnected = !m_isConnected;
 }
 
 bool VRDisplay::getFrameData(VRFrameData* frameData) {
   updatePose();
 
@@ skipping 358 matching lines @@
         m_fullscreenOrigWidth = String();
       }
       if (!m_fullscreenOrigHeight.isNull()) {
         canvas->setInlineStyleProperty(CSSPropertyWidth,
                                        m_fullscreenOrigHeight);
         m_fullscreenOrigHeight = String();
       }
     } else {
       // Can't get into this presentation mode, so nothing to do here.
     }
+    m_isPresenting = false;
     OnPresentChange();
   }
 
-  m_isPresenting = false;
   m_renderingContext = nullptr;
   m_contextGL = nullptr;
 }
 
 void VRDisplay::updateLayerBounds() {
   if (!m_display)
     return;
 
   // Set up the texture bounds for the provided layer
   device::mojom::blink::VRLayerBoundsPtr leftBounds =
@@ skipping 99 matching lines @@
 
   m_display->SubmitFrame(m_framePose.Clone());
   m_canUpdateFramePose = true;
 }
 
 Document* VRDisplay::document() {
   return m_navigatorVR->document();
 }
 
 void VRDisplay::OnPresentChange() {
+  if (m_isPresenting && !m_isValidDeviceForPresenting) {
+    VLOG(1) << __FUNCTION__ << ": device not valid, not sending event";
+    return;
+  }
   m_navigatorVR->enqueueVREvent(VRDisplayEvent::create(
       EventTypeNames::vrdisplaypresentchange, true, false, this, ""));
 }
 
 void VRDisplay::OnChanged(device::mojom::blink::VRDisplayInfoPtr display) {
   update(display);
 }
 
 void VRDisplay::OnExitPresent() {
   forceExitPresent();
@@ skipping 53 matching lines @@
   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