Add Maplike<> utility mixin class for implementing maplike interfaces

Source/modules/encryptedmedia/MediaKeyStatusMap.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 MediaKeyStatusMap_h
 #define MediaKeyStatusMap_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/UnionTypesCore.h"
 #include "core/dom/DOMArrayPiece.h"
-#include "core/dom/Iterable.h"
+#include "core/dom/Maplike.h"
 #include "platform/heap/Heap.h"
 
 namespace blink {
 
 class ExceptionState;
 class Iterator;
 class ScriptState;
 class WebData;
 
 // Represents a read-only map (to JavaScript) of key IDs and their current
 // status known to a particular session. Since it can be updated any time there
 // is a keychange event, iteration order and completeness is not guaranteed
 // if the event loop runs.
-class MediaKeyStatusMap final : public GarbageCollected<MediaKeyStatusMap>, public ScriptWrappable, public PairIterable<DOMArrayBuffer*, String> {
+class MediaKeyStatusMap final : public GarbageCollected<MediaKeyStatusMap>, public ScriptWrappable, public Maplike<ArrayBufferOrArrayBufferView, String> {
     DEFINE_WRAPPERTYPEINFO();
 private:
     // MapEntry holds the keyId (DOMArrayBuffer) and status (MediaKeyStatus as
     // String) for each entry.
     class MapEntry;
 
     // As the number of keys per session should be small, the key ids and
     // their status are kept in a list rather than a proper map.
     typedef HeapVector<Member<MapEntry>> MapType;
 
 public:
     MediaKeyStatusMap() { }
 
     void clear();
     void addEntry(WebData source, const String& status);
     const MapEntry& at(size_t) const;
 
     // IDL attributes / methods
     size_t size() const { return m_entries.size(); }
-    String get(const DOMArrayPiece& key);
-    bool has(const DOMArrayPiece& key) const;
 
     virtual void trace(Visitor*);
 
 private:
     IterationSource* startIteration(ScriptState*, ExceptionState&) override;
+    bool getMapEntry(ScriptState*, const ArrayBufferOrArrayBufferView&, String&, ExceptionState&) override;
 
     size_t indexOf(const DOMArrayPiece& key) const;
 
     MapType m_entries;
 };
 
 } // namespace blink
 
 #endif // MediaKeyStatusMap_h