Expose Cache Storage API in global window/worker scope

Source/modules/serviceworkers/GlobalCacheStorage.h

+// Copyright 2015 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 GlobalCacheStorage_h
+#define GlobalCacheStorage_h
+
+namespace blink {
+
+class CacheStorage;
+class DOMWindow;
+class ExceptionState;
+class ScriptState;
+class WorkerGlobalScope;
+
+class GlobalCacheStorage {
+public:
+    static CacheStorage* caches(ScriptState*, DOMWindow&, ExceptionState&);
+    static CacheStorage* caches(ScriptState*, WorkerGlobalScope&, ExceptionState&);
+};
+
+} // namespace blink
+
+#endif // GlobalCacheStorage_h