Allow XHR timeout attribute to be overridden after send(), per spec

Source/core/loader/ThreadableLoader.h

Index: Source/core/loader/ThreadableLoader.h
diff --git a/Source/core/loader/ThreadableLoader.h b/Source/core/loader/ThreadableLoader.h
index f562551f623e1363ec8e76599091826bc9b8553d..530bf8aac859648cbe8bdd291ca70eaf2be6b9ab 100644
--- a/Source/core/loader/ThreadableLoader.h
+++ b/Source/core/loader/ThreadableLoader.h
@@ -84,6 +84,11 @@ namespace WebCore {
         static void loadResourceSynchronously(ExecutionContext&, const ResourceRequest&, ThreadableLoaderClient&, const ThreadableLoaderOptions&);
         static PassRefPtr<ThreadableLoader> create(ExecutionContext&, ThreadableLoaderClient*, const ResourceRequest&, const ThreadableLoaderOptions&);
 
+        // A ThreadableLoader may have a timeout specified. It is possible, in some cases, for
+        // the timeout to be overridden after the request is sent (for example, XMLHttpRequests
+        // may override their timeout setting after sending).

[tyoshino (SeeGerritForStatus), 2014/05/12 09:21:17]

please explain that the timeout will be updated to (the time the load was
started) + timeoutMilliseconds, not from now.

+        virtual void overrideTimeout(unsigned long timeoutMilliseconds) = 0;
+
         virtual void cancel() = 0;
 
         virtual ~ThreadableLoader() { }