Centralize the setting of Accept headers

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 176 matching lines @@
         return WebURLRequest::RequestContextImage;
     case Resource::Media: // TODO: Split this.
         return WebURLRequest::RequestContextVideo;
     case Resource::Manifest:
         return WebURLRequest::RequestContextManifest;
     }
     ASSERT_NOT_REACHED();
     return WebURLRequest::RequestContextSubresource;
 }
 
+static void addAcceptHeader(ResourceRequest& request, Resource::Type type)
+{
+    if (type == Resource::CSSStyleSheet) {
+        DEFINE_STATIC_LOCAL(const AtomicString, acceptCSS, ("text/css,*/*;q=0.1", AtomicString::ConstructFromLiteral));
+        request.setHTTPAccept(acceptCSS);
+    } else if (type == Resource::Script) {
+        DEFINE_STATIC_LOCAL(const AtomicString, acceptScripts, ("*/*", AtomicString::ConstructFromLiteral));
+        request.setHTTPAccept(acceptScripts);
+    } else if (type == Resource::Image) {
+        DEFINE_STATIC_LOCAL(const AtomicString, acceptImages, ("image/webp,image/*,*/*;q=0.8", AtomicString::ConstructFromLiteral));
+        request.setHTTPAccept(acceptImages);
+    } else if (type == Resource::XSLStyleSheet) {
+        DEFINE_STATIC_LOCAL(const AtomicString, acceptXSLT, ("text/xml, application/xml, application/xhtml+xml, text/xsl, application/rss+xml, application/atom+xml", AtomicString::ConstructFromLiteral));
+        request.setHTTPAccept(acceptXSLT);
+    }

[Yoav Weiss, 2016/03/30 06:18:58]

What about other Resource::Types? Where are they set?
e.g. when looking at Font requests, they're set to "*/*".

Aside: When looking at navigational requests, they're set to
"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8".
Looking where that happens, I found that render_frame_impl adds that for frame
requests where accept is not set by Blink.
Maybe worth while mentioning that in a comment here?

+}
+
 ResourceFetcher::ResourceFetcher(FetchContext* newContext)
     : m_context(newContext)
     , m_archive(context().isMainFrame() ? nullptr : context().archive())
     , m_resourceTimingReportTimer(this, &ResourceFetcher::resourceTimingReportTimerFired)
     , m_autoLoadImages(true)
     , m_imagesEnabled(true)
     , m_allowStaleResources(false)
 {
 #if ENABLE(OILPAN)
     ThreadState::current()->registerPreFinalizer(this);
@@ skipping 319 matching lines @@
 }
 
 void ResourceFetcher::initializeResourceRequest(ResourceRequest& request, Resource::Type type)
 {
     if (request.getCachePolicy() == UseProtocolCachePolicy)
         request.setCachePolicy(context().resourceRequestCachePolicy(request, type));
     if (request.requestContext() == WebURLRequest::RequestContextUnspecified)
         determineRequestContext(request, type);
     if (type == Resource::LinkPrefetch)
         request.setHTTPHeaderField(HTTPNames::Purpose, "prefetch");
+    addAcceptHeader(request, type);
 
     context().addAdditionalRequestHeaders(request, (type == Resource::MainResource) ? FetchMainResource : FetchSubresource);
 }
 
 void ResourceFetcher::initializeRevalidation(const FetchRequest& request, Resource* resource)
 {
     ASSERT(resource);
     ASSERT(memoryCache()->contains(resource));
     ASSERT(resource->isLoaded());
     ASSERT(resource->canUseCacheValidator());
@@ skipping 648 matching lines @@
     visitor->trace(m_loaders);
     visitor->trace(m_nonBlockingLoaders);
 #if ENABLE(OILPAN)
     visitor->trace(m_documentResources);
     visitor->trace(m_preloads);
     visitor->trace(m_resourceTimingInfoMap);
 #endif
 }
 
 } // namespace blink