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

cc/layers/scrollbar_layer_unittest.cc

 // Copyright 2012 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 <stddef.h>
 
 #include <unordered_map>
 
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 275 matching lines @@
       gfx::PointF(), InputHandler::TOUCHSCREEN, scroll_tree, scroll_node);
   EXPECT_EQ(InputHandler::SCROLL_IGNORED, status.thread);
   EXPECT_EQ(MainThreadScrollingReason::kNotScrollable,
             status.main_thread_scrolling_reasons);
 }
 
 TEST_F(ScrollbarLayerTest, ScrollOffsetSynchronization) {
   std::unique_ptr<Scrollbar> scrollbar(new FakeScrollbar);
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   scoped_refptr<Layer> scroll_layer = Layer::Create();
+  scroll_layer->SetElementId(LayerIdToElementIdForTesting(scroll_layer->id()));
   scoped_refptr<Layer> content_layer = Layer::Create();
   scoped_refptr<Layer> scrollbar_layer = PaintedScrollbarLayer::Create(
       std::move(scrollbar), scroll_layer->id(), scroll_layer->element_id());
 
   // Choose bounds to give max_scroll_offset = (30, 50).
   layer_tree_root->SetBounds(gfx::Size(70, 150));
   scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
   scroll_layer->SetScrollOffset(gfx::ScrollOffset(10, 20));
   scroll_layer->SetBounds(gfx::Size(100, 200));
   content_layer->SetBounds(gfx::Size(100, 200));
@@ skipping 93 matching lines @@
 }
 
 TEST_F(ScrollbarLayerTest, ThumbRect) {
   scoped_refptr<Layer> root_clip_layer = Layer::Create();
   scoped_refptr<Layer> root_layer = Layer::Create();
   scoped_refptr<Layer> content_layer = Layer::Create();
   scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
       FakePaintedScrollbarLayer::Create(false, true, root_layer->id(),
                                         root_layer->element_id());
 
+  root_layer->SetElementId(LayerIdToElementIdForTesting(root_layer->id()));
   root_layer->SetScrollClipLayerId(root_clip_layer->id());
   // Give the root-clip a size that will result in MaxScrollOffset = (80, 0).
   root_clip_layer->SetBounds(gfx::Size(20, 50));
   root_layer->SetBounds(gfx::Size(100, 50));
   content_layer->SetBounds(gfx::Size(100, 50));
 
   layer_tree_host_->SetRootLayer(root_clip_layer);
   root_clip_layer->AddChild(root_layer);
   root_layer->AddChild(content_layer);
   root_layer->AddChild(scrollbar_layer);
@@ skipping 171 matching lines @@
 
 TEST_F(ScrollbarLayerTest, LayerDrivenSolidColorDrawQuads) {
   const int kThumbThickness = 3;
   const int kTrackStart = 0;
   const int kTrackLength = 10;
 
   std::unique_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, true));
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   scoped_refptr<Layer> scroll_layer = Layer::Create();
+  scroll_layer->SetElementId(LayerIdToElementIdForTesting(scroll_layer->id()));
   scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
   scoped_refptr<Layer> child1 = Layer::Create();
   scoped_refptr<Layer> child2;
   const bool kIsLeftSideVerticalScrollbar = false;
   child2 = SolidColorScrollbarLayer::Create(
       scrollbar->Orientation(), kThumbThickness, kTrackStart,
       kIsLeftSideVerticalScrollbar, scroll_layer->id(),
       scroll_layer->element_id());
   scroll_layer->AddChild(child1);
   scroll_layer->InsertChild(child2, 1);
@@ skipping 115 matching lines @@
   // Pushing changed bounds of scroll layer can lead to calling
   // OnOpacityAnimated on scrollbar layer which means OnOpacityAnimated should
   // be independent of scrollbar layer's properties as scrollbar layer can push
   // its properties after scroll layer.
   const int kThumbThickness = 3;
   const int kTrackStart = 0;
   std::unique_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, true));
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   scoped_refptr<Layer> scroll_layer = Layer::Create();
+  scroll_layer->SetElementId(LayerIdToElementIdForTesting(scroll_layer->id()));
   scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
   scoped_refptr<Layer> child1 = Layer::Create();
   scoped_refptr<Layer> scrollbar_layer;
   const bool kIsLeftSideVerticalScrollbar = false;
   scrollbar_layer = SolidColorScrollbarLayer::Create(
       scrollbar->Orientation(), kThumbThickness, kTrackStart,
       kIsLeftSideVerticalScrollbar, scroll_layer->id(),
       scroll_layer->element_id());
-  scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
   scroll_layer->AddChild(child1);
   scroll_layer->InsertChild(scrollbar_layer, 1);
   layer_tree_root->AddChild(scroll_layer);
   layer_tree_host_->SetRootLayer(layer_tree_root);
 
   layer_tree_root->SetBounds(gfx::Size(2, 2));
   scroll_layer->SetBounds(gfx::Size(10, 10));
   layer_tree_host_->UpdateLayers();
   layer_tree_host_->CommitAndCreateLayerImplTree();
   LayerTreeHostImpl* host_impl = layer_tree_host_->host_impl();
@@ skipping 494 matching lines @@
   TestScale(gfx::Rect(1240, 0, 15, 1333), 2.7754839f);
   TestScale(gfx::Rect(1240, 0, 15, 677), 2.46677136f);
 
   // Horizontal Scrollbars.
   TestScale(gfx::Rect(0, 1240, 1333, 15), 2.7754839f);
   TestScale(gfx::Rect(0, 1240, 677, 15), 2.46677136f);
 }
 
 }  // namespace
 }  // namespace cc