Introduce InspectorIdentifiers<> and use it to assign/lookup LocalFrame and DocumentLoader

Source/core/inspector/InspectorIdentifiers.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 InspectorIdentifiers_h
+#define InspectorIdentifiers_h
+
+#include "core/dom/WeakIdentifierMap.h"
+#include "core/inspector/IdentifiersFactory.h"
+
+namespace blink {
+
+struct InspectorIdentifierGenerator {
+    using IdentifierType = String;
+    static IdentifierType next()
+    {
+        return IdentifiersFactory::createIdentifier();
+    }
+};
+
+template<typename T> class InspectorIdentifiers {
+public:
+    static String identifier(T* object) { return map().identifier(object); }
+    static T* lookup(const String& identifier) { return map().lookup(identifier); }
+
+private:
+    using IdentifierMap = WeakIdentifierMap<T, InspectorIdentifierGenerator>;
+    InspectorIdentifiers() { }
+
+    static IdentifierMap& map()
+    {
+        DEFINE_STATIC_LOCAL(typename IdentifierMap::ReferenceType, identifierMap, (new IdentifierMap));
+        return *identifierMap;
+    }
+};
+
+} // namespace blink
+
+#endif // #ifndef InspectorIdentifiers_h