Implementation for feature policy - fullscreen

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

Index: third_party/WebKit/Source/core/dom/Fullscreen.cpp
diff --git a/third_party/WebKit/Source/core/dom/Fullscreen.cpp b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
index ff1331bd4cadc423dc311e1626746ce7ce733867..d3539bd4f9210ac1e77848dd3e29ac1049c4f4a1 100644
--- a/third_party/WebKit/Source/core/dom/Fullscreen.cpp
+++ b/third_party/WebKit/Source/core/dom/Fullscreen.cpp
@@ -29,6 +29,7 @@
 
 #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"
@@ -100,10 +101,43 @@ bool allowedToRequestFullscreen(Document& document) {
 }
 
 // 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