Property tree code must account for parent offsets of fixed layers

cc/trees/layer_tree_host_common_unittest.cc

Index: cc/trees/layer_tree_host_common_unittest.cc
diff --git a/cc/trees/layer_tree_host_common_unittest.cc b/cc/trees/layer_tree_host_common_unittest.cc
index 6f05035428a285c7fc1f13411b77b6a52f067b07..b6c3f67ffd0a78e82f18a6cf998bb2d6ccc4830f 100644
--- a/cc/trees/layer_tree_host_common_unittest.cc
+++ b/cc/trees/layer_tree_host_common_unittest.cc
@@ -8812,5 +8812,42 @@ TEST_F(LayerTreeHostCommonTest, AnimatedFilterCreatesRenderSurface) {
   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