Property tree code must account for parent offsets of fixed layers

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 <algorithm>
 #include <set>
 
 #include "cc/animation/layer_animation_controller.h"
@@ skipping 8794 matching lines @@
 
   EXPECT_TRUE(root->filters().IsEmpty());
   EXPECT_TRUE(child->filters().IsEmpty());
   EXPECT_TRUE(grandchild->filters().IsEmpty());
 
   EXPECT_FALSE(root->FilterIsAnimating());
   EXPECT_TRUE(child->FilterIsAnimating());
   EXPECT_FALSE(grandchild->FilterIsAnimating());
 }
 
+// Ensures that the property tree code accounts for offsets between fixed
+// position layers and their respective containers.
+TEST_F(LayerTreeHostCommonTest, PropertyTreesAccountForFixedParentOffset) {
+  scoped_refptr<Layer> root = Layer::Create();
+  scoped_refptr<Layer> child = Layer::Create();
+  scoped_refptr<LayerWithForcedDrawsContent> grandchild =
+      make_scoped_refptr(new LayerWithForcedDrawsContent());
+
+  root->AddChild(child);
+  child->AddChild(grandchild);
+
+  gfx::Transform identity_transform;
+  SetLayerPropertiesForTesting(root.get(), identity_transform, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(50, 50), true, false);
+  SetLayerPropertiesForTesting(child.get(), identity_transform, gfx::Point3F(),
+                               gfx::PointF(1000, 1000), gfx::Size(50, 50), true,
+                               false);
+  SetLayerPropertiesForTesting(grandchild.get(), identity_transform,
+                               gfx::Point3F(), gfx::PointF(-1000, -1000),
+                               gfx::Size(50, 50), true, false);
+
+  root->SetMasksToBounds(true);
+  root->SetIsContainerForFixedPositionLayers(true);
+  LayerPositionConstraint constraint;
+  constraint.set_is_fixed_position(true);
+  grandchild->SetPositionConstraint(constraint);
+
+  root->SetIsContainerForFixedPositionLayers(true);
+
+  scoped_ptr<FakeLayerTreeHost> host(CreateFakeLayerTreeHost());
+  host->SetRootLayer(root);
+
+  // Property tree verification will fail if position of child is not accounted

[enne (OOO), 2015/03/02 01:12:26]

Verification will not persist in the future.  Maybe check draw transforms
explicitly?

[Ian Vollick, 2015/03/02 01:28:00]

Great point -- if we were to switch to property trees, this test would silently
test nothing. I've switched it to test the visible content rect from property
trees directly. Once we switch to property trees for real, this could will
obviously need to be updated when Layer::visible_rect_from_property_trees is
deleted.

+  // for in the tree building.
+  ExecuteCalculateDrawProperties(root.get());
+}
+
 }  // namespace
 }  // namespace cc