Implementation for feature policy - fullscreen

third_party/WebKit/Source/core/dom/Fullscreen.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 11 matching lines @@
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #include "core/dom/Fullscreen.h"
 
+#include "bindings/core/v8/ConditionalFeatures.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/StyleEngine.h"
 #include "core/events/Event.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/HostsUsingFeatures.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
 #include "core/html/HTMLIFrameElement.h"
@@ skipping 51 matching lines @@
   String message = ExceptionMessages::failedToExecute(
       "requestFullscreen", "Element",
       "API can only be initiated by a user gesture.");
   document.addConsoleMessage(
       ConsoleMessage::create(JSMessageSource, WarningMessageLevel, message));
 
   return false;
 }
 
 // https://fullscreen.spec.whatwg.org/#fullscreen-is-supported
-bool fullscreenIsSupported(const Document& document) {
+// TODO(lunalu): update the placement of the feature policy code once it is in
+// https://fullscreen.spec.whatwg.org/.
+bool fullscreenIsSupported(Document& document) {
+  Frame* frame = document.frame();

[foolip, 2016/12/02 10:52:09]

document.frame() returns a LocalFrame*, so you can use that and skip the DCHECK
and cast.

I think all call sites guarantee that document.frame() can't be null here, but
that's a bit brittle, so I'd say also throw in `if (!frame) return false`;

[lunalu1, 2016/12/02 19:22:07]

Done.

+  DCHECK(frame->isLocalFrame());
+  if (!isFeatureEnabledInFrame(blink::kFullscreenFeature,
+                               toLocalFrame(frame))) {
+    if (RuntimeEnabledFeatures::featurePolicyEnabled()) {
+      document.addConsoleMessage(ConsoleMessage::create(
+          JSMessageSource, WarningMessageLevel,
+          "Fullscreen API is disabled by feature policy for this frame"));
+      return false;
+    }
+  }
   // Fullscreen is supported if there is no previously-established user
   // preference, security risk, or platform limitation.
   return !document.settings() || document.settings()->fullscreenSupported();
 }
 
 // https://fullscreen.spec.whatwg.org/#fullscreen-element-ready-check
 bool fullscreenElementReady(const Element& element) {
   // A fullscreen element ready check for an element |element| returns true if
   // all of the following are true, and false otherwise:
 
@@ skipping 653 matching lines @@
 
 DEFINE_TRACE(Fullscreen) {
   visitor->trace(m_currentFullScreenElement);
   visitor->trace(m_fullscreenElementStack);
   visitor->trace(m_eventQueue);
   Supplement<Document>::trace(visitor);
   ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink