Ensure navigator.getVRDisplays always resolves.

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

 // Copyright 2015 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/VRController.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/vr/NavigatorVR.h"
 #include "modules/vr/VRGetDevicesCallback.h"
 #include "public/platform/InterfaceProvider.h"
 
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 VRController::VRController(NavigatorVR* navigatorVR)
     : ContextLifecycleObserver(navigatorVR->document()),
       m_navigatorVR(navigatorVR),
       m_displaySynced(false),
       m_binding(this) {
   navigatorVR->document()->frame()->interfaceProvider()->getInterface(
       mojo::GetProxy(&m_service));
+  m_service.set_connection_error_handler(convertToBaseCallback(
+      WTF::bind(&VRController::dispose, wrapWeakPersistent(this))));
   m_service->SetClient(
       m_binding.CreateInterfacePtrAndBind(),
       convertToBaseCallback(
           WTF::bind(&VRController::onDisplaysSynced, wrapPersistent(this))));
   ThreadState::current()->registerPreFinalizer(this);
 }
 
 VRController::~VRController() {}
 
 void VRController::getDisplays(ScriptPromiseResolver* resolver) {
-  if (!m_service) {
-    DOMException* exception = DOMException::create(
-        InvalidStateError, "The service is no longer active.");
-    resolver->reject(exception);
-    return;
-  }
-
-  // If we've previously synced the VRDisplays just return the current list.
-  if (m_displaySynced) {
+  // If we've previously synced the VRDisplays or no longer have a valid service
+  // connection just return the current list. In the case of the service being
+  // disconnected this will be an empty array.
+  if (!m_service || m_displaySynced) {
     resolver->resolve(m_displays);
     return;
   }
 
   // Otherwise we're still waiting for the full list of displays to be populated
   // so queue up the promise for resolution when onDisplaysSynced is called.
   m_pendingGetDevicesCallbacks.append(
       makeUnique<VRGetDevicesCallback>(resolver));
 }
 
@@ skipping 47 matching lines @@
 
 void VRController::dispose() {
   // If the document context was destroyed, shut down the client connection
   // and never call the mojo service again.
   m_service.reset();
   m_binding.Close();
 
   // Shutdown all displays' message pipe
   for (size_t i = 0; i < m_displays.size(); ++i)
     m_displays[i]->dispose();
+
+  m_displays.clear();
+
+  // Ensure that any outstanding getDisplays promises are resolved.
+  onGetDisplays();
 }
 
 DEFINE_TRACE(VRController) {
   visitor->trace(m_navigatorVR);
   visitor->trace(m_displays);
 
   ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink