Replace layer id with Element id for tracking scrollbar animation controllers

cc/test/fake_painted_scrollbar_layer.cc

 // Copyright 2013 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/test/fake_painted_scrollbar_layer.h"
 
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "cc/test/fake_scrollbar.h"
 
 namespace cc {
 
 scoped_refptr<FakePaintedScrollbarLayer> FakePaintedScrollbarLayer::Create(
     bool paint_during_update,
     bool has_thumb,
-    int scrolling_layer_id) {
+    int scrolling_layer_id,
+    ElementId scrolling_element_id) {
   return Create(paint_during_update, has_thumb, HORIZONTAL, false, false,
-                scrolling_layer_id);
+                scrolling_layer_id, scrolling_element_id);
 }
 
 scoped_refptr<FakePaintedScrollbarLayer> FakePaintedScrollbarLayer::Create(
     bool paint_during_update,
     bool has_thumb,
     ScrollbarOrientation orientation,
     bool is_left_side_vertical_scrollbar,
     bool is_overlay,
-    int scrolling_layer_id) {
+    int scrolling_layer_id,
+    ElementId scrolling_element_id) {
   FakeScrollbar* fake_scrollbar =
       new FakeScrollbar(paint_during_update, has_thumb, orientation,
                         is_left_side_vertical_scrollbar, is_overlay);
-  return make_scoped_refptr(
-      new FakePaintedScrollbarLayer(fake_scrollbar, scrolling_layer_id));
+  return make_scoped_refptr(new FakePaintedScrollbarLayer(
+      fake_scrollbar, scrolling_layer_id, scrolling_element_id));
 }
 
 FakePaintedScrollbarLayer::FakePaintedScrollbarLayer(
     FakeScrollbar* fake_scrollbar,
-    int scrolling_layer_id)
+    int scrolling_layer_id,
+    ElementId scrolling_element_id)
     : PaintedScrollbarLayer(std::unique_ptr<Scrollbar>(fake_scrollbar),
-                            scrolling_layer_id),
+                            scrolling_layer_id,
+                            scrolling_element_id),
       update_count_(0),
       push_properties_count_(0),
       fake_scrollbar_(fake_scrollbar) {
   SetBounds(gfx::Size(1, 1));
   SetIsDrawable(true);
 }
 
 FakePaintedScrollbarLayer::~FakePaintedScrollbarLayer() {}
 
 bool FakePaintedScrollbarLayer::Update() {
   bool updated = PaintedScrollbarLayer::Update();
   ++update_count_;
   return updated;
 }
 
 void FakePaintedScrollbarLayer::PushPropertiesTo(LayerImpl* layer) {
   PaintedScrollbarLayer::PushPropertiesTo(layer);
   ++push_properties_count_;
 }
 
 std::unique_ptr<base::AutoReset<bool>>
 FakePaintedScrollbarLayer::IgnoreSetNeedsCommit() {
   return base::MakeUnique<base::AutoReset<bool>>(&ignore_set_needs_commit_,
                                                  true);
 }
 
 }  // namespace cc