Implement the infrastructure of creating WorkerFetchContext in worker global scope.

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

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 154 matching lines @@
                                  const FetchParameters::ResourceWidth&,
                                  ResourceRequest&);
 
   MHTMLArchive* Archive() const override;
 
   ResourceLoadPriority ModifyPriorityForExperiments(
       ResourceLoadPriority) override;
 
   RefPtr<WebTaskRunner> LoadingTaskRunner() const override;
 
+  std::unique_ptr<WebURLLoader> CreateURLLoader() override;
+
   DECLARE_VIRTUAL_TRACE();
 
  private:
   FrameFetchContext(DocumentLoader*, Document*);
 
   // m_documentLoader is null when loading resources from an HTML import
   // and in such cases we use the document loader of the importing frame.
   // Convenient accessors below can be used to transparently access the
   // relevant document loader or frame in either cases without null-checks.
   // TODO(kinuko): Remove constness, these return non-const members.
@@ skipping 22 matching lines @@
       SecurityViolationReportingPolicy,
       ResourceRequest::RedirectStatus,
       ContentSecurityPolicy::CheckHeaderType) const;
 
   Member<DocumentLoader> document_loader_;
 };
 
 }  // namespace blink
 
 #endif