[cc] Fix crash when adding a child layer to its own parent.

cc/layer_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 "config.h"
 
 #include "cc/layer.h"
 
 #include "cc/keyframed_animation_curve.h"
 #include "cc/layer_impl.h"
@@ skipping 146 matching lines @@
     EXECUTE_AND_VERIFY_SET_NEEDS_COMMIT_BEHAVIOR(1, parent->addChild(child));
 
     ASSERT_EQ(static_cast<size_t>(1), parent->children().size());
     EXPECT_EQ(child.get(), parent->children()[0]);
     EXPECT_EQ(parent.get(), child->parent());
     EXPECT_EQ(parent.get(), child->rootLayer());
 
     EXECUTE_AND_VERIFY_SET_NEEDS_COMMIT_BEHAVIOR(AtLeast(1), child->removeFromParent());
 }
 
+TEST_F(LayerTest, addSameChildTwice)
+{
+    scoped_refptr<Layer> parent = Layer::create();
+    scoped_refptr<Layer> child = Layer::create();
+
+    parent->setLayerTreeHost(m_layerTreeHost.get());

[danakj, 2012/11/12 21:47:23]

Do m_layerTreeHost->setRootLayer(parent) instead

[Ted C, 2012/11/12 22:15:45]

Done.

+
+    ASSERT_EQ(static_cast<size_t>(0), parent->children().size());
+
+    parent->addChild(child);
+    ASSERT_EQ(static_cast<size_t>(1), parent->children().size());
+    EXPECT_EQ(parent.get(), child->parent());
+
+    parent->addChild(child);
+    ASSERT_EQ(static_cast<size_t>(1), parent->children().size());
+    EXPECT_EQ(parent.get(), child->parent());
+}
+
 TEST_F(LayerTest, insertChild)
 {
     scoped_refptr<Layer> parent = Layer::create();
     scoped_refptr<Layer> child1 = Layer::create();
     scoped_refptr<Layer> child2 = Layer::create();
     scoped_refptr<Layer> child3 = Layer::create();
     scoped_refptr<Layer> child4 = Layer::create();
 
     parent->setLayerTreeHost(m_layerTreeHost.get());
 
@@ skipping 616 matching lines @@
     scoped_refptr<MockLayer> layer(new MockLayer);
     EXPECT_FALSE(layer->needsDisplay());
     layer->setBounds(gfx::Size(0, 10));
     EXPECT_FALSE(layer->needsDisplay());
     layer->setBounds(gfx::Size(10, 10));
     EXPECT_TRUE(layer->needsDisplay());
 }
 
 
 }  // anonymous namespace