Change cc::ElementId to be a uint64_t

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

Index: third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.cpp b/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.cpp
index ce23989edab2a0a3a723afd0f96cfb3910a5dd70..a20ef2f3e609bb80af7ba233f7cf91cb45b69496 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.cpp
@@ -38,7 +38,7 @@ bool IsAncestorOf(const PropertyNode* ancestor, const PropertyNode* child) {
   return child == ancestor;
 }
 
-const CompositorElementId PropertyTreeState::GetCompositorElementId(
+CompositorElementId PropertyTreeState::GetCompositorElementId(
     const CompositorElementIdSet& element_ids) const {
 // The effect or transform nodes could have a compositor element id. The order
 // doesn't matter as the element id should be the same on all that have a
@@ -52,7 +52,7 @@ const CompositorElementId PropertyTreeState::GetCompositorElementId(
 // previously attached to a layer). This is an interim step while we pursue
 // broader rework of animation subsystem noted in http://crbug.com/709137.
 #if DCHECK_IS_ON()
-  CompositorElementId expected_element_id;
+  CompositorElementId expected_element_id = kInvalidElementId;
   CompositorElementId effect_element_id = Effect()->GetCompositorElementId();
   if (effect_element_id && !element_ids.Contains(effect_element_id)) {
     expected_element_id = effect_element_id;