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

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositorTest.cpp

 // Copyright 2016 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 "platform/graphics/compositing/PaintArtifactCompositor.h"
 
 #include <memory>
 
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 752 matching lines @@
   // Only one content layer, and the first child layer is the dummy layer for
   // the transform node.
   const cc::Layer* transform_node_layer = RootLayer()->children()[0].get();
   EXPECT_EQ(transform_node_layer->id(), transform_node.owning_layer_id);
   auto transform_node_index =
       GetPropertyTrees().transform_tree.FindNodeIndexFromOwningLayerId(
           transform_node_layer->id());
   EXPECT_EQ(transform_node_index, transform_node.id);
 
   EXPECT_EQ(0u, scroll_client.did_scroll_count);
+  // TODO(pdr): The PaintArtifactCompositor should set the scroll clip layer id
+  // so the Layer is scrollable. This call should be removed.
+  layer->SetScrollClipLayerId(layer->id());
   layer->SetScrollOffsetFromImplSide(gfx::ScrollOffset(1, 2));
   EXPECT_EQ(1u, scroll_client.did_scroll_count);
   EXPECT_EQ(gfx::ScrollOffset(1, 2), scroll_client.last_scroll_offset);
 }
 
 TEST_F(PaintArtifactCompositorTestWithPropertyTrees, TransformUnderScrollNode) {
   RefPtr<TransformPaintPropertyNode> scroll_translation =
       TransformPaintPropertyNode::CreateScrollTranslation(
           TransformPaintPropertyNode::Root(),
           TransformationMatrix().Translate(7, 9), FloatPoint3D(), false, 0,
@@ skipping 1474 matching lines @@
   TestPaintArtifact artifact;
   artifact
       .Chunk(TransformPaintPropertyNode::Root(), ClipPaintPropertyNode::Root(),
              visibleEffect)
       .RectDrawing(FloatRect(0, 0, 100, 100), Color::kBlack);
   Update(artifact.Build());
   ASSERT_EQ(0u, ContentLayerCount());
 }
 
 }  // namespace blink