Implement the infrastructure of creating WorkerFetchContext in worker global scope.

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

Index: third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
index 9123c3a589958554e23054b60dc1689ba417ab4d..dfcdc18d8c69f27134a99ce3807eb23d250c373b 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
@@ -80,6 +80,7 @@
 #include "platform/weborigin/SchemeRegistry.h"
 #include "platform/weborigin/SecurityPolicy.h"
 #include "platform/wtf/Vector.h"
+#include "public/platform/Platform.h"
 #include "public/platform/WebCachePolicy.h"
 #include "public/platform/WebInsecureRequestPolicy.h"
 #include "public/platform/WebViewScheduler.h"
@@ -305,6 +306,10 @@ FrameFetchContext::~FrameFetchContext() {
   document_loader_ = nullptr;
 }
 
+WebURLLoader* FrameFetchContext::CreateURLLoader() {
+  return Platform::Current()->CreateURLLoader();
+}
+
 LocalFrame* FrameFetchContext::FrameOfImportsController() const {
   DCHECK(document_);
   HTMLImportsController* imports_controller = document_->ImportsController();