Refactor LayerTreeImpl's scrollbar map to be keyed on element ids

cc/input/scrollbar_animation_controller.cc

 // Copyright 2014 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.
 
 #include "cc/input/scrollbar_animation_controller.h"
 
 #include <algorithm>
 
 #include "base/time/time.h"
 #include "cc/trees/layer_tree_impl.h"
 
 namespace cc {
 
 std::unique_ptr<ScrollbarAnimationController>
 ScrollbarAnimationController::CreateScrollbarAnimationControllerAndroid(
-    int scroll_layer_id,
+    ElementId scroll_element_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta fade_out_delay,
     base::TimeDelta fade_out_resize_delay,
     base::TimeDelta fade_out_duration) {
   return base::WrapUnique(new ScrollbarAnimationController(
-      scroll_layer_id, client, fade_out_delay, fade_out_resize_delay,
+      scroll_element_id, client, fade_out_delay, fade_out_resize_delay,
       fade_out_duration));
 }
 
 std::unique_ptr<ScrollbarAnimationController>
 ScrollbarAnimationController::CreateScrollbarAnimationControllerAuraOverlay(
-    int scroll_layer_id,
+    ElementId scroll_element_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta show_delay,
     base::TimeDelta fade_out_delay,
     base::TimeDelta fade_out_resize_delay,
     base::TimeDelta fade_out_duration,
     base::TimeDelta thinning_duration) {
   return base::WrapUnique(new ScrollbarAnimationController(
-      scroll_layer_id, client, show_delay, fade_out_delay,
+      scroll_element_id, client, show_delay, fade_out_delay,
       fade_out_resize_delay, fade_out_duration, thinning_duration));
 }
 
 ScrollbarAnimationController::ScrollbarAnimationController(
-    int scroll_layer_id,
+    ElementId scroll_element_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta fade_out_delay,
     base::TimeDelta fade_out_resize_delay,
     base::TimeDelta fade_out_duration)
     : client_(client),
       fade_out_delay_(fade_out_delay),
       fade_out_resize_delay_(fade_out_resize_delay),
       need_trigger_scrollbar_show_(false),
       is_animating_(false),
-      scroll_layer_id_(scroll_layer_id),
+      scroll_element_id_(scroll_element_id),
       currently_scrolling_(false),
       show_in_fast_scroll_(false),
       opacity_(0.0f),
       fade_out_duration_(fade_out_duration),
       show_scrollbars_on_scroll_gesture_(false),
       need_thinning_animation_(false),
       weak_factory_(this) {
   ApplyOpacityToScrollbars(0.0f);
 }
 
 ScrollbarAnimationController::ScrollbarAnimationController(
-    int scroll_layer_id,
+    ElementId scroll_element_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta show_delay,
     base::TimeDelta fade_out_delay,
     base::TimeDelta fade_out_resize_delay,
     base::TimeDelta fade_out_duration,
     base::TimeDelta thinning_duration)
     : client_(client),
       show_delay_(show_delay),
       fade_out_delay_(fade_out_delay),
       fade_out_resize_delay_(fade_out_resize_delay),
       need_trigger_scrollbar_show_(false),
       is_animating_(false),
-      scroll_layer_id_(scroll_layer_id),
+      scroll_element_id_(scroll_element_id),
       currently_scrolling_(false),
       show_in_fast_scroll_(false),
       opacity_(0.0f),
       fade_out_duration_(fade_out_duration),
       show_scrollbars_on_scroll_gesture_(true),
       need_thinning_animation_(true),
       weak_factory_(this) {
   vertical_controller_ = SingleScrollbarAnimationControllerThinning::Create(
-      scroll_layer_id, ScrollbarOrientation::VERTICAL, client,
+      scroll_element_id, ScrollbarOrientation::VERTICAL, client,
       thinning_duration);
   horizontal_controller_ = SingleScrollbarAnimationControllerThinning::Create(
-      scroll_layer_id, ScrollbarOrientation::HORIZONTAL, client,
+      scroll_element_id, ScrollbarOrientation::HORIZONTAL, client,
       thinning_duration);
   ApplyOpacityToScrollbars(0.0f);
 }
 
 ScrollbarAnimationController::~ScrollbarAnimationController() {}
 
 ScrollbarSet ScrollbarAnimationController::Scrollbars() const {
-  return client_->ScrollbarsFor(scroll_layer_id_);
+  return client_->ScrollbarsFor(scroll_element_id_);
 }
 
 SingleScrollbarAnimationControllerThinning&
 ScrollbarAnimationController::GetScrollbarAnimationController(
     ScrollbarOrientation orientation) const {
   DCHECK(need_thinning_animation_);
   if (orientation == ScrollbarOrientation::VERTICAL)
     return *(vertical_controller_.get());
   else
     return *(horizontal_controller_.get());
@@ skipping 270 matching lines @@
   if (opacity_ != opacity)
     client_->SetNeedsRedrawForScrollbarAnimation();
 
   opacity_ = opacity;
 
   if (previouslyVisible != currentlyVisible)
     client_->DidChangeScrollbarVisibility();
 }
 
 }  // namespace cc