Change cc::ElementId to be a uint64_t

third_party/WebKit/Source/platform/graphics/CompositorElementId.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 "platform/graphics/CompositorElementId.h"
 
 namespace blink {
 
 CompositorElementId CreateCompositorElementId(
-    int dom_node_id,
+    DOMNodeId dom_node_id,
     CompositorSubElementId sub_element_id) {
-  return CompositorElementId(dom_node_id, static_cast<int>(sub_element_id));
+  DCHECK(dom_node_id > 0 &&
+         dom_node_id < std::numeric_limits<DOMNodeId>::max() /
+                           static_cast<unsigned>(
+                               CompositorSubElementId::kNumSubElementTypes));
+  cc::ElementIdType id =
+      dom_node_id << 2;  // Shift to make room for sub_element_id enum bits.
+  id += static_cast<uint64_t>(sub_element_id);
+  return CompositorElementId(id);
+}
+
+DOMNodeId DomNodeIdFromCompositorElementId(CompositorElementId element_id) {
+  return element_id.id_ >> 2;
+}
+
+CompositorSubElementId SubElementIdFromCompositorElementId(
+    CompositorElementId element_id) {
+  return static_cast<CompositorSubElementId>(
+      element_id.id_ %
+      static_cast<unsigned>(CompositorSubElementId::kNumSubElementTypes));
 }
 
 }  // namespace blink