Correct for enclosing layers scroll position in sticky_data->main_thread_offset

cc/trees/layer_tree_host_common_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_common.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 7633 matching lines @@
   // And if we scroll a little further it remains there.
   SetScrollOffsetDelta(scroller_impl, gfx::Vector2dF(0.f, 10.f));
   ExecuteCalculateDrawProperties(root_impl);
   EXPECT_VECTOR2DF_EQ(
       gfx::Vector2dF(-5.f, 10.f),
       sticky_pos_impl->ScreenSpaceTransform().To2dTranslation());
 }
 
 // This tests the main thread updates with a composited sticky container. In
 // this case the position received from main is relative to the container but
-// the constraint rects are relative to the ancestor scroller.
+// the constraint rects are relative to the ancestor scroller. The
+// parent_relative_sticky_box_offset from main also includes the scroll offset.
 TEST_F(LayerTreeHostCommonTest, StickyPositionCompositedContainer) {
   scoped_refptr<Layer> root = Layer::Create();
   scoped_refptr<Layer> container = Layer::Create();
   scoped_refptr<Layer> scroller = Layer::Create();
   scoped_refptr<Layer> sticky_container = Layer::Create();
   scoped_refptr<Layer> sticky_pos = Layer::Create();
   root->AddChild(container);
   container->AddChild(scroller);
   scroller->AddChild(sticky_container);
   sticky_container->AddChild(sticky_pos);
@@ skipping 47 matching lines @@
 
   // Scroll past the sticking point, the Y coordinate should now be clamped.
   SetScrollOffsetDelta(scroller_impl, gfx::Vector2dF(0.f, 25.f));
   ExecuteCalculateDrawProperties(root_impl);
   EXPECT_VECTOR2DF_EQ(
       gfx::Vector2dF(20.f, 10.f),
       sticky_pos_impl->ScreenSpaceTransform().To2dTranslation());
 
   // Now the main thread commits the new position of the sticky element.
   scroller->SetScrollOffset(gfx::ScrollOffset(0, 25));
+  sticky_position.parent_relative_sticky_box_offset += gfx::Vector2d(0, 25);
+  sticky_pos->SetStickyPositionConstraint(sticky_position);
   sticky_pos->SetPosition(gfx::PointF(0, 15));
   ExecuteCalculateDrawProperties(root.get());
   host()->host_impl()->CreatePendingTree();
   host()->CommitAndCreatePendingTree();
   host()->host_impl()->ActivateSyncTree();
   layer_tree_impl = host()->host_impl()->active_tree();
   root_impl = layer_tree_impl->LayerById(root->id());
   scroller_impl = layer_tree_impl->LayerById(scroller->id());
   sticky_pos_impl = layer_tree_impl->LayerById(sticky_pos->id());
 
@@ skipping 3020 matching lines @@
   EXPECT_EQ(scroll_child6.id, grand_child10->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent3->scroll_tree_index());
   EXPECT_EQ(scroll_child7.id, child8->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent4->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, child9->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, grand_child12->scroll_tree_index());
 }
 
 }  // namespace
 }  // namespace cc