Change cc::ElementId to be a uint64_t

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index e8f170ad5caaf8da29f5ceeb5fb40deb2508ca76..ce74150c22ce43bbbc4c087bbbf35c417b1e661d 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -3542,13 +3542,15 @@ static void CollectScrollDeltas(ScrollAndScaleSet* scroll_info,
 
 static void CollectScrollbarUpdates(
     ScrollAndScaleSet* scroll_info,
-    std::unordered_map<ElementId,
-                       std::unique_ptr<ScrollbarAnimationController>,
-                       ElementIdHash>* controllers) {
+    std::unordered_map<ElementId::Id,
+                       std::unique_ptr<ScrollbarAnimationController>>*
+        controllers) {
   scroll_info->scrollbars.reserve(controllers->size());
   for (auto& pair : *controllers) {
+    ElementId element_id;
+    element_id.id = pair.first;
     scroll_info->scrollbars.push_back(LayerTreeHostCommon::ScrollbarsUpdateInfo(
-        pair.first, pair.second->ScrollbarsHidden()));
+        element_id, pair.second->ScrollbarsHidden()));
   }
 }
 
@@ -3694,13 +3696,13 @@ void LayerTreeHostImpl::RegisterScrollbarAnimationController(
   if (ScrollbarAnimationControllerForElementId(scroll_element_id))
     return;
 
-  scrollbar_animation_controllers_[scroll_element_id] =
+  scrollbar_animation_controllers_[scroll_element_id.id] =
       active_tree_->CreateScrollbarAnimationController(scroll_element_id);
 }
 
 void LayerTreeHostImpl::UnregisterScrollbarAnimationController(
     ElementId scroll_element_id) {
-  scrollbar_animation_controllers_.erase(scroll_element_id);
+  scrollbar_animation_controllers_.erase(scroll_element_id.id);
 }
 
 ScrollbarAnimationController*
@@ -3711,7 +3713,7 @@ LayerTreeHostImpl::ScrollbarAnimationControllerForElementId(
   if (InnerViewportScrollLayer() && OuterViewportScrollLayer() &&
       scroll_element_id == InnerViewportScrollLayer()->element_id())
     scroll_element_id = OuterViewportScrollLayer()->element_id();
-  auto i = scrollbar_animation_controllers_.find(scroll_element_id);
+  auto i = scrollbar_animation_controllers_.find(scroll_element_id.id);
   if (i == scrollbar_animation_controllers_.end())
     return nullptr;
   return i->second.get();