Sending an async GET request for doc.written blocked scripts.

third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 145 matching lines @@
     if (type == Resource::Script) {
         if (FetchRequest::LazyLoad == request.defer())
             priority = ResourceLoadPriorityLow;
         else if (request.forPreload() && m_imageFetched)
             priority = ResourceLoadPriorityMedium;
     } else if (FetchRequest::LazyLoad == request.defer()) {
         // A deferred load of type Raw is a link rel=preload, which should be Low instead of VeryLow.
         priority = type == Resource::Raw ? ResourceLoadPriorityLow : ResourceLoadPriorityVeryLow;
     }
 
+    priority = request.resourceRequest().computePriorityForInterventions(priority);

[Nate Chapin, 2016/08/22 19:47:03]

This seems like overkill at first glance. Is there a reason marking the request
as LazyLoad is insufficient?

[shivanisha, 2016/08/22 20:44:00]

LazyLoad results in priority ResourceLoadPriorityLow which maps to net::LOWEST
but we want a priority net::IDLE for this case.

[Nate Chapin, 2016/08/22 20:55:12]

Ah, I forgot about the script-specific LazyLoad priority.

Adding an Idle value to the ResourceFetcher::DeferOption enum seemed like it'd
be cleaner than plumbing this through ResourceRequest. Can we do that instead?

[shivanisha, 2016/08/23 01:04:46]

That's a good suggestion. Done.

+
     // A manually set priority acts as a floor. This is used to ensure that synchronous requests
     // are always given the highest possible priority, as well as to ensure that there isn't priority
     // churn if images move in and out of the viewport, or is displayed more than once, both in and out
     // of the viewport.
     return std::max(context().modifyPriorityForExperiments(priority), request.resourceRequest().priority());
 }
 
 static void populateResourceTiming(ResourceTimingInfo* info, Resource* resource)
 {
     info->setInitialRequest(resource->resourceRequest());
@@ skipping 1143 matching lines @@
     visitor->trace(m_context);
     visitor->trace(m_archive);
     visitor->trace(m_loaders);
     visitor->trace(m_nonBlockingLoaders);
     visitor->trace(m_documentResources);
     visitor->trace(m_preloads);
     visitor->trace(m_resourceTimingInfoMap);
 }
 
 } // namespace blink