Replace layer id with Element id for tracking scrollbar animation controllers

cc/trees/layer_tree_host_impl.h

 // Copyright 2011 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 CC_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <stddef.h>
 
 #include <bitset>
@@ skipping 304 matching lines @@
 
   // Prevents notifying the |client_| when an impl side invalidation request is
   // made. When unblocked, the disabled request will immediately be called.
   virtual void BlockImplSideInvalidationRequestsForTesting(bool block);
 
   // Resets all of the trees to an empty state.
   void ResetTreesForTesting();
 
   size_t SourceAnimationFrameNumberForTesting() const;
 
-  void RegisterScrollbarAnimationController(int scroll_layer_id);
-  void UnregisterScrollbarAnimationController(int scroll_layer_id);
-  ScrollbarAnimationController* ScrollbarAnimationControllerForId(
-      int scroll_layer_id) const;
+  void RegisterScrollbarAnimationController(int scroll_layer_id,
+                                            ElementId scroll_element_id);
+  void UnregisterScrollbarAnimationController(ElementId scroll_element_id);
+  ScrollbarAnimationController* ScrollbarAnimationControllerForElementId(
+      ElementId scroll_element_id) const;
 
   DrawMode GetDrawMode() const;
 
   // Viewport size in draw space: this size is in physical pixels and is used
   // for draw properties, tilings, quads and render passes.
   gfx::Size DrawViewportSize() const;
 
   // Viewport rect in view space used for tiling prioritization.
   const gfx::Rect ViewportRectForTilePriority() const;
 
@@ skipping 417 matching lines @@
   std::unique_ptr<LayerTreeImpl> pending_tree_;
 
   // In impl-side painting mode, inert tree with layers that can be recycled
   // by the next sync from the main thread.
   std::unique_ptr<LayerTreeImpl> recycle_tree_;
 
   InputHandlerClient* input_handler_client_;
   bool did_lock_scrolling_layer_;
   bool wheel_scrolling_;
   bool scroll_affects_scroll_handler_;
-  int scroll_layer_id_mouse_currently_over_;
-  int scroll_layer_id_mouse_currently_captured_;
+  ElementId scroll_element_id_mouse_currently_over_;
+  ElementId scroll_element_id_mouse_currently_captured_;
 
   std::vector<std::unique_ptr<SwapPromise>>
       swap_promises_for_main_thread_scroll_update_;
 
   // An object to implement the ScrollElasticityHelper interface and
   // hold all state related to elasticity. May be NULL if never requested.
   std::unique_ptr<ScrollElasticityHelper> scroll_elasticity_helper_;
 
   bool tile_priorities_dirty_;
 
@@ skipping 39 matching lines @@
   gfx::Transform external_transform_;
   gfx::Rect external_viewport_;
   gfx::Rect viewport_rect_for_tile_priority_;
   bool resourceless_software_draw_;
 
   gfx::Rect viewport_damage_rect_;
 
   std::unique_ptr<MutatorHost> mutator_host_;
   std::set<VideoFrameController*> video_frame_controllers_;
 
-  // Map from scroll layer ID to scrollbar animation controller.
+  // Map from scroll element ID to scrollbar animation controller.
   // There is one animation controller per pair of overlay scrollbars.
-  std::unordered_map<int, std::unique_ptr<ScrollbarAnimationController>>
+  std::unordered_map<ElementId,
+                     std::unique_ptr<ScrollbarAnimationController>,
+                     ElementIdHash>
       scrollbar_animation_controllers_;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
   MicroBenchmarkControllerImpl micro_benchmark_controller_;
   std::unique_ptr<SynchronousTaskGraphRunner>
       single_thread_synchronous_task_graph_runner_;
 
   // Optional callback to notify of new tree activations.
   base::Closure tree_activation_callback_;
 
@@ skipping 31 matching lines @@
   bool has_scrolled_by_touch_;
 
   bool touchpad_and_wheel_scroll_latching_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_