Blink CompositorWorker: Use CompositorElementId and CompositorIdToElementMap.

third_party/WebKit/Source/core/dom/CompositorIdToElementMap.cpp

+// Copyright 2016 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.
+
+#include "core/dom/CompositorIdToElementMap.h"
+
+#include "core/dom/Element.h"
+#include "core/dom/WeakIdentifierMap.h"
+#include "platform/heap/Handle.h"
+#include "wtf/HashMap.h"
+
+namespace blink {
+
+class WeakIdToElementMap : public GarbageCollected<WeakIdToElementMap> {
+public:
+    static void put(CompositorElementId elementId, Element* element)
+    {
+        ASSERT(element);
+        instance().m_IdToElement->set(elementId, element);
+    }
+
+    static Element* lookup(CompositorElementId elementId)
+    {
+        return instance().m_IdToElement->get(elementId);
+    }
+
+    static void notifyObjectDestroyed(Element* object) { }
+
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_IdToElement);
+    }
+
+private:
+    static WeakIdToElementMap& instance()
+    {
+        DEFINE_STATIC_LOCAL(WeakIdToElementMap, mapInstance, (new WeakIdToElementMap()));
+        return mapInstance;
+    }
+
+    WeakIdToElementMap()
+        : m_IdToElement(new IdToElement())
+    {
+    }
+
+    using IdToElement = HeapHashMap<CompositorElementId, WeakMember<Element>>;

[esprehn, 2016/05/10 22:46:57]

I don't want to add more maps, use DOMNodeIds for this. We shouldn't have other
maps that do the same thing.

[loyso (OOO), 2016/05/12 05:55:39]

Acknowledged.

+    Member<IdToElement> m_IdToElement;
+};
+
+
+// static
+void CompositorIdToElementMap::registerElement(Element& element)
+{
+    ASSERT(element.compositorElementId());
+    WeakIdToElementMap::put(element.compositorElementId(), &element);
+}
+
+// static
+Element* CompositorIdToElementMap::getById(CompositorElementId elementId)
+{
+    return WeakIdToElementMap::lookup(elementId);
+}
+
+} // namespace blink