Centralize the setting of Accept headers

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

Index: third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
diff --git a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
index 4f63ece7f63ceceb57ed50d1d1c235aeb163cbbb..2c9479b901cec751c5ad484ead903f63ebf5a095 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
@@ -194,6 +194,23 @@ static WebURLRequest::RequestContext requestContextFromType(bool isMainFrame, Re
     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())
@@ -533,6 +550,7 @@ void ResourceFetcher::initializeResourceRequest(ResourceRequest& request, Resour
         determineRequestContext(request, type);
     if (type == Resource::LinkPrefetch)
         request.setHTTPHeaderField(HTTPNames::Purpose, "prefetch");
+    addAcceptHeader(request, type);
 
     context().addAdditionalRequestHeaders(request, (type == Resource::MainResource) ? FetchMainResource : FetchSubresource);
 }