Change cc::ElementId to be a uint64_t

cc/animation/scroll_offset_animations.cc

Index: cc/animation/scroll_offset_animations.cc
diff --git a/cc/animation/scroll_offset_animations.cc b/cc/animation/scroll_offset_animations.cc
index 3998c89a8db44388fe152823863d3d82201168fc..e2a8da473f716946caef49a318e28fda1bfba0bb 100644
--- a/cc/animation/scroll_offset_animations.cc
+++ b/cc/animation/scroll_offset_animations.cc
@@ -20,8 +20,8 @@ ScrollOffsetAnimations::~ScrollOffsetAnimations() {}
 
 ScrollOffsetAnimationUpdate ScrollOffsetAnimations::GetUpdateForElementId(
     ElementId element_id) const {
-  DCHECK(element_id);
-  auto iter = element_to_update_map_.find(element_id);
+  DCHECK(element_id.id);
+  auto iter = element_to_update_map_.find(element_id.id);
   return iter == element_to_update_map_.end()
              ? ScrollOffsetAnimationUpdate(element_id)
              : iter->second;
@@ -29,19 +29,19 @@ ScrollOffsetAnimationUpdate ScrollOffsetAnimations::GetUpdateForElementId(
 
 void ScrollOffsetAnimations::AddAdjustmentUpdate(ElementId element_id,
                                                  gfx::Vector2dF adjustment) {
-  DCHECK(element_id);
+  DCHECK(element_id.id);
   ScrollOffsetAnimationUpdate update = GetUpdateForElementId(element_id);
   update.adjustment_ += adjustment;
-  element_to_update_map_[element_id] = update;
+  element_to_update_map_[element_id.id] = update;
   animation_host_->SetNeedsCommit();
   animation_host_->SetNeedsPushProperties();
 }
 
 void ScrollOffsetAnimations::AddTakeoverUpdate(ElementId element_id) {
-  DCHECK(element_id);
+  DCHECK(element_id.id);
   ScrollOffsetAnimationUpdate update = GetUpdateForElementId(element_id);
   update.takeover_ = true;
-  element_to_update_map_[element_id] = update;
+  element_to_update_map_[element_id.id] = update;
   animation_host_->SetNeedsCommit();
   animation_host_->SetNeedsPushProperties();
 }