Reject requestPresent requests when fullscreen is not enabled.

third_party/WebKit/Source/modules/vr/NavigatorVR.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/NavigatorVR.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/dom/Fullscreen.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Navigator.h"
 #include "core/frame/UseCounter.h"
 #include "core/page/Page.h"
 #include "modules/vr/VRController.h"
 #include "modules/vr/VRDisplay.h"
 #include "modules/vr/VRGetDevicesCallback.h"
 #include "modules/vr/VRPose.h"
 #include "platform/UserGestureIndicator.h"
@@ skipping 103 matching lines @@
   if (!page())
     return;
   if (m_controller) {
     m_controller->setListeningForActivate(page()->isPageVisible() &&
                                           m_listeningForActivate);
   }
 }
 
 void NavigatorVR::didAddEventListener(LocalDOMWindow* window,
                                       const AtomicString& eventType) {
-  if (eventType == EventTypeNames::vrdisplayactivate) {
+  // TODO(mthiesse): Remove fullscreen requirement for presentation. See
+  // crbug.com/687369
+  if (eventType == EventTypeNames::vrdisplayactivate &&
+      supplementable()->frame() && supplementable()->frame()->document() &&
+      Fullscreen::fullscreenEnabled(*supplementable()->frame()->document())) {
     controller()->setListeningForActivate(true);
     m_listeningForActivate = true;
   } else if (eventType == EventTypeNames::vrdisplayconnect) {
     // If the page is listening for connection events make sure we've created a
     // controller so that we'll be notified of new devices.
     controller();
   }
 }
 
 void NavigatorVR::didRemoveEventListener(LocalDOMWindow* window,
                                          const AtomicString& eventType) {
   if (eventType == EventTypeNames::vrdisplayactivate &&
       !window->hasEventListeners(EventTypeNames::vrdisplayactivate)) {
     controller()->setListeningForActivate(false);
     m_listeningForActivate = false;
   }
 }
 
 void NavigatorVR::didRemoveAllEventListeners(LocalDOMWindow* window) {
   if (m_controller) {
     m_controller->setListeningForActivate(false);
     m_listeningForActivate = false;
   }
 }
 
 }  // namespace blink