SameSite: Correctly set requests' initiator for new tabs.

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.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 4141 matching lines @@
     // FIXME: If this document came from the file system, the HTML5
     // specificiation tells us to read the last modification date from the file
     // system.
     if (!foundDate)
         date.setMillisecondsSinceEpochForDateTime(convertToLocalTime(currentTimeMS()));
     return String::format("%02d/%02d/%04d %02d:%02d:%02d", date.month() + 1, date.monthDay(), date.fullYear(), date.hour(), date.minute(), date.second());
 }
 
 const KURL Document::firstPartyForCookies() const
 {
+    // If this is an imported document, grab its master document's first-party:
+    if (importsController() && importsController()->master() && importsController()->master() != this)
+        return importsController()->master()->firstPartyForCookies();

[Mike West, 2016/06/21 09:01:01]

Note also: I could split this and the 'render_frame_impl.cc'
'firstPartyForCookies()' piece out into a separate patch if you like. The one
requires the other, as the current implementation is busted for imports (they
have no `frame()`, so asking them for a first-party causes a null-deref.

+
     // TODO(mkwst): This doesn't correctly handle sandboxed documents; we want to look at their URL,
     // but we can't because we don't know what it is.
     Frame* top = frame()->tree().top();
     KURL topDocumentURL = top->isLocalFrame()
         ? toLocalFrame(top)->document()->url()
         : KURL(KURL(), top->securityContext()->getSecurityOrigin()->toString());
     if (SchemeRegistry::shouldTreatURLSchemeAsFirstPartyWhenTopLevel(topDocumentURL.protocol()))
         return topDocumentURL;
 
     // We're intentionally using the URL of each document rather than the document's SecurityOrigin.
@@ skipping 1846 matching lines @@
 }
 
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().getString().utf8().data());
 }
 #endif