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) {
+  LocalFrame* frame = document.frame();
+  if (!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();
+  bool fullscreenSupported =
+      !document.settings() || document.settings()->fullscreenSupported();
+
+  if (!RuntimeEnabledFeatures::featurePolicyEnabled()) {
+    return fullscreenSupported;
+  }
+
+  // TODO(lunalu): clean all of this up once iframe attributes are supported
+  // for feature policy.
+  if (Frame* parent = frame->tree().parent()) {
+    // If FeaturePolicy is enabled, check the fullscreen is not disabled by
+    // policy in the parent frame.
+    if (fullscreenSupported &&
+        parent->securityContext()->getFeaturePolicy()->isFeatureEnabled(

[foolip, 2016/12/07 16:09:25]

I was working on https://codereview.chromium.org/2557943002/ today when I had to
wonder if it was OK to skip this test in the case of cross-process iframes. Will
this check that fullscreen is allowed by the policy for all parent frames up the
chain? If not, then it will be possible for some intermediate but cross-process
frame to go fullscreen in violation of the feature policy.

+            kFullscreenFeature)) {
+      return true;
+    }
+  }
+  // Even if the iframe allowfullscreen attribute is not present, allow
+  // fullscreen to be enabled by feature policy.
+  else if (isFeatureEnabledInFrame(kFullscreenFeature, frame)) {
+    return true;
+  }
+
+  document.addConsoleMessage(ConsoleMessage::create(
+      JSMessageSource, WarningMessageLevel,
+      "Fullscreen API is disabled by feature policy for this frame"));
+  return false;
 }
 
 // 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:
 
   // |element| is in a document.
   if (!element.isConnected())
     return false;
@@ skipping 650 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