Add HTMLPreloadScanner support for <link rel=preload>

third_party/WebKit/Source/core/html/parser/PreloadRequest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/html/parser/PreloadRequest.h"
 
 #include "core/dom/Document.h"
 #include "core/fetch/FetchInitiatorInfo.h"
+#include "core/fetch/ResourceFetcher.h"
 #include "platform/CrossOriginAttributeValue.h"
 
 namespace blink {
 
 bool PreloadRequest::isSafeToSendToAnotherThread() const
 {
     return m_initiatorName.isSafeToSendToAnotherThread()
         && m_charset.isSafeToSendToAnotherThread()
         && m_resourceURL.isSafeToSendToAnotherThread()
         && m_baseURL.isSafeToSendToAnotherThread();
 }
 
 KURL PreloadRequest::completeURL(Document* document)
 {
     if (!m_baseURL.isEmpty())
         return document->completeURLWithOverride(m_resourceURL, m_baseURL);
     return document->completeURL(m_resourceURL);
 }
 
 FetchRequest PreloadRequest::resourceRequest(Document* document)
 {
     ASSERT(isMainThread());
     FetchInitiatorInfo initiatorInfo;
     initiatorInfo.name = AtomicString(m_initiatorName);
     initiatorInfo.position = m_initiatorPosition;
     ResourceRequest resourceRequest(completeURL(document));
     resourceRequest.setHTTPReferrer(SecurityPolicy::generateReferrer(m_referrerPolicy, resourceRequest.url(), document->outgoingReferrer()));
+    ResourceFetcher::determineRequestContext(resourceRequest, m_resourceType, false);
     FetchRequest request(resourceRequest, initiatorInfo);
 
     if (m_resourceType == Resource::ImportResource) {
         SecurityOrigin* securityOrigin = document->contextDocument()->securityOrigin();
         request.setCrossOriginAccessControl(securityOrigin, CrossOriginAttributeAnonymous);
     }
     if (m_crossOrigin != CrossOriginAttributeNotSet)
         request.setCrossOriginAccessControl(document->securityOrigin(), m_crossOrigin);
     request.setDefer(m_defer);
     request.setResourceWidth(m_resourceWidth);
     request.clientHintsPreferences().updateFrom(m_clientHintsPreferences);
     request.setIntegrityMetadata(m_integrityMetadata);
 
+    if (m_requestType == RequestTypeLinkRelPreload)
+        request.setAvoidBlockingOnLoad(true);

[Nate Chapin, 2016/01/12 03:28:17]

It's unfortunate to need to set this in a second place, but I don't see a good
way to avoid that.

[Yoav Weiss, 2016/01/12 06:37:56]

agree

     return request;
 }
 
 }