Blink CompositorWorker: Use CompositorElementId and CompositorIdToElementMap.

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

Index: third_party/WebKit/Source/core/dom/CompositorIdToElementMap.h
diff --git a/third_party/WebKit/Source/core/dom/CompositorIdToElementMap.h b/third_party/WebKit/Source/core/dom/CompositorIdToElementMap.h
new file mode 100644
index 0000000000000000000000000000000000000000..7af8c8d6d74b020248ca02205da4aa97a668c856
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/CompositorIdToElementMap.h
@@ -0,0 +1,26 @@
+// 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.
+
+#ifndef CompositorIdToElementMap_h
+#define CompositorIdToElementMap_h
+
+#include "core/CoreExport.h"
+#include "platform/graphics/CompositorElementId.h"
+#include "wtf/Allocator.h"
+
+namespace blink {
+
+class Element;
+
+class CORE_EXPORT CompositorIdToElementMap {
+    STATIC_ONLY(CompositorIdToElementMap);
+public:
+    static void registerElement(Element&);
+    static Element* getById(CompositorElementId);
+};
+
+} // namespace blink
+
+
+#endif // DOMNodeIds_h