Make ResourceLoadPriority calculation simpler

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

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
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  *     * Redistributions in binary form must reproduce the above
@@ skipping 279 matching lines @@
     ResourceFetcher::determineRequestContext(resourceRequest, resourceType, false);
     FetchRequest linkRequest(resourceRequest, FetchInitiatorTypeNames::link, document.encodingName());
 
     if (crossOrigin != CrossOriginAttributeNotSet)
         linkRequest.setCrossOriginAccessControl(document.getSecurityOrigin(), crossOrigin);
     Settings* settings = document.settings();
     if (settings && settings->logPreload())
         document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preload triggered for " + href.host() + href.path())));
     linkRequest.setForPreload(true, monotonicallyIncreasingTime());
     linkRequest.setLinkPreload(true);
-    linkRequest.setPriority(document.fetcher()->loadPriority(resourceType, linkRequest));
+    if (resourceType == Resource::LinkPreload)
+        linkRequest.setDefer(FetchRequest::LazyLoad);

[Yoav Weiss, 2016/06/30 09:09:14]

I think you left that one out, as we said LinkPreload shouldn't be LazyLoad.
Also - how are tests passing with this change? :|

In general, I'll try to see if we can remove LinkPreload as a type entirely (and
just set it to whatever XHR is).

Also, I'm assuming that you deleted the `setPriority()` as it's no longer
needed, since priority is now set on the resource. Is that correct?

[Nate Chapin, 2016/07/20 19:05:03]

The tests currently expect LinkPreloads to be priority Low, instead of the usual
priority High for XHRs and other Raw resources. ResourceFetcher now
special-cases Raw LazyLoads to get that behavior. If you'd like me to change
what the tests expect instead, I'm happy to do that, but I was aiming to keep
this cleanup-only.
I *think* this priority difference is the only behavioral difference between the
LinkPreload and Raw types, so it should be straightforward?
s/resource/request/, but otherwise correct. The priority should now only be set
directly on the ResourceRequest, by FetchRequest::makeSynchrnous() for sync
requests, and by ResourceFetcher for all other cases.

     return document.loader()->startPreload(resourceType, linkRequest);
 }
 
 void LinkLoader::loadLinksFromHeader(const String& headerValue, const KURL& baseURL, Document* document, const NetworkHintsInterface& networkHintsInterface,
     CanLoadResources canLoadResources, ViewportDescriptionWrapper* viewportDescriptionWrapper)
 {
     if (!document || headerValue.isEmpty())
         return;
     LinkHeaderSet headerSet(headerValue);
     for (auto& header : headerSet) {
@@ skipping 82 matching lines @@
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_client);
     visitor->trace(m_prerender);
     visitor->trace(m_linkPreloadResourceClient);
     ResourceOwner<Resource, ResourceClient>::trace(visitor);
     PrerenderClient::trace(visitor);
 }
 
 } // namespace blink