Replicate feature policy headers to remote frames

third_party/WebKit/Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
@@ skipping 578 matching lines @@
       featurePolicy->setHeaderPolicy(
           m_documentLoader->response().httpHeaderField(
               HTTPNames::Feature_Policy),
           messages);
       for (auto& message : messages) {
         m_frame->document()->addConsoleMessage(ConsoleMessage::create(
             OtherMessageSource, ErrorMessageLevel,
             "Error with Feature-Policy header: " + message));
       }
       m_frame->document()->setFeaturePolicy(std::move(featurePolicy));
+      if (client()) {
+        client()->didSetFeaturePolicyHeader(
+            m_documentLoader->response().httpHeaderField(
+                HTTPNames::Feature_Policy));
+      }

[Mike West, 2016/11/08 12:12:23]

An approach that you might wish to consider would be moving this up to the
browser process entirely. That is, rather than parsing the header in Blink and
pushing a policy up through the browser, you could parse the policy in the
browser, store it on the frame tree, and forcibly apply parent's policy to child
frames when the browser created them for each navigation.

[iclelland, 2016/11/08 14:25:45]

Since a frame can also set policy for itself -- it can disable synchronous
script loading, or remove v8 features, I think we'll need to have the policy set
before we can continue with parsing the document; moving it to the browser
process would mean that we have to block on that process switch (twice), which I
was hoping to avoid.

     }
   }
 
   if (m_documentLoader) {
     String referrerPolicyHeader = m_documentLoader->response().httpHeaderField(
         HTTPNames::Referrer_Policy);
     if (!referrerPolicyHeader.isNull()) {
       m_frame->document()->parseAndSetReferrerPolicy(referrerPolicyHeader);
     }
   }
@@ skipping 1338 matching lines @@
                          m_documentLoader ? m_documentLoader->url() : String());
   return tracedValue;
 }
 
 inline void FrameLoader::takeObjectSnapshot() const {
   TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID("loading", "FrameLoader", this,
                                       toTracedValue());
 }
 
 }  // namespace blink