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

cc/layer_unittest.cc

Index: cc/layer_unittest.cc
diff --git a/cc/layer_unittest.cc b/cc/layer_unittest.cc
index 2bbbef4db906dea6fde27092e775716adcde02b4..6105f6f00f4b5a3b877871155855bd158465fc55 100644
--- a/cc/layer_unittest.cc
+++ b/cc/layer_unittest.cc
@@ -164,6 +164,24 @@ TEST_F(LayerTest, addAndRemoveChild)
     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();
+
+    m_layerTreeHost->setRootLayer(parent);
+
+    ASSERT_EQ(static_cast<size_t>(0u), parent->children().size());

[danakj, 2012/11/12 22:31:48]

You shouldn't need the static_casts then :)

[tfarina, 2012/11/12 22:36:27]

yep, that is what I suggested:
s/static_cast<size_t>(0)/0u :)

[Ted C, 2012/11/12 22:59:03]

Done :-)  That's what I get for trying to get a change done right before a
meeting.

+
+    parent->addChild(child);
+    ASSERT_EQ(static_cast<size_t>(1u), parent->children().size());
+    EXPECT_EQ(parent.get(), child->parent());
+
+    parent->addChild(child);
+    ASSERT_EQ(static_cast<size_t>(1u), parent->children().size());
+    EXPECT_EQ(parent.get(), child->parent());
+}
+
 TEST_F(LayerTest, insertChild)
 {
     scoped_refptr<Layer> parent = Layer::create();