Reset property tree indices when layer is removed from layer tree

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 9579 matching lines @@
   scoped_ptr<FakeLayerTreeHost> host(CreateFakeLayerTreeHost());
   host->SetRootLayer(root);
 
   EXPECT_EQ(root->num_layer_or_descendants_with_input_handler(), 0);
   ExecuteCalculateDrawProperties(root.get());
   EXPECT_EQ(root->num_layer_or_descendants_with_input_handler(), 1);
   child->SetHaveWheelEventHandlers(false);
   EXPECT_EQ(root->num_layer_or_descendants_with_input_handler(), 0);
 }
 
+TEST_F(LayerTreeHostCommonTest, ResetPropertyTreeIndices) {
+  gfx::Transform identity;
+  gfx::Transform translate_z;
+  translate_z.Translate3d(0, 0, 10);
+
+  scoped_refptr<Layer> root = Layer::Create();
+  SetLayerPropertiesForTesting(root.get(), identity, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(800, 800), true, false);
+
+  scoped_refptr<Layer> child = Layer::Create();
+  SetLayerPropertiesForTesting(child.get(), translate_z, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(100, 100), true, false);
+
+  root->AddChild(child);
+
+  scoped_ptr<FakeLayerTreeHost> host(CreateFakeLayerTreeHost());
+  host->SetRootLayer(root);
+
+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+  EXPECT_NE(-1, child->transform_tree_index());
+
+  child->RemoveFromParent();
+
+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+  EXPECT_EQ(-1, child->transform_tree_index());
+}
+
 }  // namespace
 }  // namespace cc