Reject requestPresent requests when fullscreen is not enabled.

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 220 matching lines @@
   // allowed outside a user gesture so that the presented content may be
   // updated.
   if (firstPresent && !UserGestureIndicator::utilizeUserGesture()) {
     DOMException* exception = DOMException::create(
         InvalidStateError, "API can only be initiated by a user gesture.");
     resolver->reject(exception);
     ReportPresentationResult(PresentationResult::NotInitiatedByUserGesture);
     return promise;
   }
 
+  // TODO(mthiesse): Remove fullscreen requirement for presentation. See
+  // crbug.com/687369
+  Document* doc = this->document();
+  if (!doc || !Fullscreen::fullscreenEnabled(*doc)) {
+    DOMException* exception =
+        DOMException::create(InvalidStateError, "Fullscreen is not enabled.");
+    resolver->reject(exception);
+    ReportPresentationResult(PresentationResult::FullscreenNotEnabled);
+    return promise;
+  }
+
   // A valid number of layers must be provided in order to present.
   if (layers.size() == 0 || layers.size() > m_capabilities->maxLayers()) {
     forceExitPresent();
     DOMException* exception =
         DOMException::create(InvalidStateError, "Invalid number of layers.");
     resolver->reject(exception);
     ReportPresentationResult(PresentationResult::InvalidNumberOfLayers);
     return promise;
   }
 
@@ skipping 493 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