[ServiceWorker] Make fetch() method better conformance with the spec.

Source/modules/serviceworkers/FetchManager.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef FetchManager_h
 #define FetchManager_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 class ExecutionContext;
+class FetchRequestData;
 class ScriptState;
 class ResourceRequest;
 
 class FetchManager {
 public:
     FetchManager(ExecutionContext*);
     ~FetchManager();
-    ScriptPromise fetch(ScriptState*, PassOwnPtr<ResourceRequest>);
+    ScriptPromise fetch(ScriptState*, PassRefPtr<FetchRequestData>);
 
     static bool isSimpleMethod(const String&);
     static bool isForbiddenMethod(const String&);
     static bool isUsefulMethod(const String&);
 private:
     class Loader;
 
     // Removes loader from |m_loaders|.
     void onLoaderFinished(Loader*);
 
     ExecutionContext* m_executionContext;
     HashSet<OwnPtr<Loader> > m_loaders;
 };
 
 } // namespace blink
 
 #endif // FetchManager_h