Change cc::ElementId to be a uint64_t

third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h

 // 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 PropertyTreeState_h
 #define PropertyTreeState_h
 
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
@@ skipping 44 matching lines @@
   }
   void SetEffect(RefPtr<const EffectPaintPropertyNode> node) {
     effect_ = std::move(node);
   }
 
   static const PropertyTreeState& Root();
 
   // Returns the compositor element id, if any, for this property state. If
   // neither the effect nor transform nodes have a compositor element id then a
   // default instance is returned.
-  const CompositorElementId GetCompositorElementId(
+  CompositorElementId GetCompositorElementId(
       const CompositorElementIdSet& element_ids) const;
 
   enum InnermostNode {
     kNone,  // None means that all nodes are their root values
     kTransform,
     kClip,
     kEffect,
   };
 
   // There is always a well-defined order in which the transform, clip
@@ skipping 105 matching lines @@
   }
 
   HashMap<const PropertyTreeNode*, String> node_to_debug_string_;
 };
 
 #endif
 
 }  // namespace blink
 
 #endif  // PropertyTreeState_h