Add initial link preload support

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 28184d9b90ce261197c39d9beb35b74fced4b313..179d2c135270b4c161f4480d94a7a1d8299824fc 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -333,6 +333,13 @@ ResourcePtr<Resource> ResourceFetcher::fetchLinkResource(Resource::Type type, Fe
     return requestResource(type, request);
 }
 
+ResourcePtr<Resource> ResourceFetcher::fetchLinkPreloadResource(Resource::Type type, FetchRequest& request)
+{
+    ASSERT(request.resourceRequest().frameType() == WebURLRequest::FrameTypeNone);

[Mike West, 2015/04/07 06:26:28]

Should this have a matching `preload` context as well?

[Yoav Weiss, 2015/04/07 07:26:14]

Quite possible. Do you think it should be part of the current CL, or can that be
added later on, after I decouple context from priority?

[Mike West, 2015/04/07 12:23:01]

If you already know that you need the context, then adding it in this CL should
be pretty straightforward. If the context is debatable (there's a GitHub issue,
right?), then adding it later is fine. In that case, I'd suggest adding a TODO
here.

+    determineRequestContext(request.mutableResourceRequest(), type);
+    return requestResource(type, request);
+}
+
 ResourcePtr<RawResource> ResourceFetcher::fetchRawResource(FetchRequest& request)
 {
     ASSERT(request.resourceRequest().frameType() == WebURLRequest::FrameTypeNone);