Rewrite Layer::SetScrollOffset{FromImplSide} property tree fast-path

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 419 matching lines @@
 
   // Under-scroll (thumb position should clamp and be unchanged).
   root_layer->SetScrollOffset(gfx::ScrollOffset(-5, 0));
 
   UPDATE_AND_EXTRACT_LAYER_POINTERS();
   EXPECT_EQ(gfx::Rect(10, 0, 4, 10).ToString(),
             scrollbar_layer_impl->ComputeThumbQuadRect().ToString());
 
   // Over-scroll (thumb position should clamp on the far side).
   root_layer->SetScrollOffset(gfx::ScrollOffset(85, 0));
+  layer_tree_host_->UpdateLayers();
 
   UPDATE_AND_EXTRACT_LAYER_POINTERS();
   EXPECT_EQ(gfx::Rect(56, 0, 4, 10).ToString(),
             scrollbar_layer_impl->ComputeThumbQuadRect().ToString());
 
   // Change thumb thickness and length.
   scrollbar_layer->fake_scrollbar()->set_thumb_thickness(4);
   scrollbar_layer->fake_scrollbar()->set_thumb_length(6);
 
   UPDATE_AND_EXTRACT_LAYER_POINTERS();
@@ skipping 452 matching lines @@
 }
 
 class ScrollbarLayerTestResourceCreationAndRelease : public ScrollbarLayerTest {
  public:
   void TestResourceUpload(int num_updates,
                           size_t expected_resources,
                           int expected_created,
                           int expected_deleted,
                           bool use_solid_color_scrollbar) {
     std::unique_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, false));
+    scoped_refptr<Layer> root_clip_layer = Layer::Create();
     scoped_refptr<Layer> layer_tree_root = Layer::Create();
     scoped_refptr<Layer> content_layer = Layer::Create();
     scoped_refptr<Layer> scrollbar_layer;
     if (use_solid_color_scrollbar) {
       const int kThumbThickness = 3;
       const int kTrackStart = 0;
       const bool kIsLeftSideVerticalScrollbar = false;
       scrollbar_layer = SolidColorScrollbarLayer::Create(
           scrollbar->Orientation(), kThumbThickness, kTrackStart,
           kIsLeftSideVerticalScrollbar, layer_tree_root->element_id());
     } else {
       scrollbar_layer = PaintedScrollbarLayer::Create(
           std::move(scrollbar), layer_tree_root->element_id());
     }
     layer_tree_root->AddChild(content_layer);
     layer_tree_root->AddChild(scrollbar_layer);
 
     layer_tree_host_->SetRootLayer(layer_tree_root);
 
     scrollbar_layer->SetIsDrawable(true);
     scrollbar_layer->SetBounds(gfx::Size(100, 100));
+    layer_tree_root->SetScrollClipLayerId(root_clip_layer->id());
     layer_tree_root->SetScrollOffset(gfx::ScrollOffset(10, 20));
     layer_tree_root->SetBounds(gfx::Size(100, 200));
     content_layer->SetBounds(gfx::Size(100, 200));
     scrollbar_layer->set_visible_layer_rect(gfx::Rect(0, 0, 100, 200));
 
     testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());
     EXPECT_EQ(scrollbar_layer->GetLayerTreeHostForTesting(),
               layer_tree_host_.get());
 
     for (int update_counter = 0; update_counter < num_updates; update_counter++)
@@ skipping 327 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