Replicate feature policy container policies.

third_party/WebKit/Source/core/dom/Document.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, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 5095 matching lines @@
     const KURL& about_blank_url = BlankURL();
     should_use_parent_base_url = (base_url_override == about_blank_url);
   }
   if (should_use_parent_base_url) {
     if (Document* parent = ParentDocument())
       base_url_from_parent = &parent->BaseURL();
   }
   return base_url_from_parent ? *base_url_from_parent : base_url_override;
 }
 
+// static
+bool Document::ShouldInheritSecurityOriginFromOwner(const KURL& url) {
+  // https://html.spec.whatwg.org/multipage/browsers.html#origin
+  //
+  // If a Document is the initial "about:blank" document The origin and
+  // effective script origin of the Document are those it was assigned when its
+  // browsing context was created.
+  //
+  // Note: We generalize this to all "blank" URLs and invalid URLs because we
+  // treat all of these URLs as about:blank.
+  return url.IsEmpty() || url.ProtocolIsAbout();
+}
+
 KURL Document::OpenSearchDescriptionURL() {
   static const char kOpenSearchMIMEType[] =
       "application/opensearchdescription+xml";
   static const char kOpenSearchRelation[] = "search";
 
   // FIXME: Why do only top-level frames have openSearchDescriptionURLs?
   if (!GetFrame() || GetFrame()->Tree().Parent())
     return KURL();
 
   // FIXME: Why do we need to wait for load completion?
@@ skipping 1526 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->Url().GetString().Utf8().Data());
 }
 #endif