Transfer LayerImpl ownership to LayerTreeImpl

cc/trees/layer_tree_host_unittest_damage.cc

Index: cc/trees/layer_tree_host_unittest_damage.cc
diff --git a/cc/trees/layer_tree_host_unittest_damage.cc b/cc/trees/layer_tree_host_unittest_damage.cc
index fdb3e17870995fb41351f019840cd5d9cf2d58fc..76c26f6682e9c35bf8fdbf75506167a702213575 100644
--- a/cc/trees/layer_tree_host_unittest_damage.cc
+++ b/cc/trees/layer_tree_host_unittest_damage.cc
@@ -411,8 +411,8 @@ class LayerTreeHostDamageTestScrollbarDoesDamage
     ++did_swaps_;
     EXPECT_TRUE(result);
     LayerImpl* root = host_impl->active_tree()->root_layer();
-    LayerImpl* scroll_clip_layer = root->children()[0].get();
-    LayerImpl* scroll_layer = scroll_clip_layer->children()[0].get();
+    LayerImpl* scroll_clip_layer = root->children()[0];
+    LayerImpl* scroll_layer = scroll_clip_layer->children()[0];
     switch (did_swaps_) {
       case 1:
         // Test that modifying the position of the content layer (not
@@ -504,8 +504,8 @@ class LayerTreeHostDamageTestScrollbarCommitDoesNoDamage
     ++did_swaps_;
     EXPECT_TRUE(result);
     LayerImpl* root = host_impl->active_tree()->root_layer();
-    LayerImpl* scroll_clip_layer = root->children()[0].get();
-    LayerImpl* scroll_layer = scroll_clip_layer->children()[0].get();
+    LayerImpl* scroll_clip_layer = root->children()[0];
+    LayerImpl* scroll_layer = scroll_clip_layer->children()[0];
     switch (did_swaps_) {
       case 1:
         // Scroll on the thread.  This should damage the scrollbar for the