Revert of Revert of Mixed Content: Move subframe checks into ResourceFetcher.

Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 358 matching lines @@
         }
         timing()->addRedirect(redirectResponse.url(), newRequest.url());
     }
 
     // If we're fielding a redirect in response to a POST, force a load from origin, since
     // this is a common site technique to return to a page viewing some data that the POST
     // just modified.
     if (newRequest.cachePolicy() == UseProtocolCachePolicy && isRedirectAfterPost(newRequest, redirectResponse))
         newRequest.setCachePolicy(ReloadBypassingCache);
 
-    // If this is a sub-frame, check for mixed content blocking against the parent frame.
-    if (Frame* parent = m_frame->tree().parent()) {
-        if (parent->isLocalFrame() && !toLocalFrame(parent)->loader().mixedContentChecker()->canFrameInsecureContent(toLocalFrame(parent)->document()->securityOrigin(), newRequest.url())) {
-            cancelMainResourceLoad(ResourceError::cancelledError(newRequest.url()));
-            return;
-        }
-    }
-
     m_request = newRequest;
 
     if (redirectResponse.isNull())
         return;
 
     appendRedirect(newRequest.url());
     frameLoader()->client()->dispatchDidReceiveServerRedirectForProvisionalLoad();
     if (!shouldContinueForNavigationPolicy(newRequest, CheckContentSecurityPolicy))
         cancelMainResourceLoad(ResourceError::cancelledError(m_request.url()));
 }
@@ skipping 426 matching lines @@
 // This is only called by FrameLoader::replaceDocumentWhileExecutingJavaScriptURL()
 void DocumentLoader::replaceDocumentWhileExecutingJavaScriptURL(const DocumentInit& init, const String& source, Document* ownerDocument)
 {
     m_writer = createWriterFor(ownerDocument, init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 } // namespace blink