cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

cc/trees/tree_synchronizer_unittest.cc

Index: cc/trees/tree_synchronizer_unittest.cc
diff --git a/cc/trees/tree_synchronizer_unittest.cc b/cc/trees/tree_synchronizer_unittest.cc
index b0e211418d36ebe338682416e155ccc860db0883..007c85781262cb9ba206aab504810739f1a785f7 100644
--- a/cc/trees/tree_synchronizer_unittest.cc
+++ b/cc/trees/tree_synchronizer_unittest.cc
@@ -56,7 +56,7 @@ class MockLayer : public Layer {
 
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
       OVERRIDE {
-    return MockLayerImpl::Create(tree_impl, layer_id_).PassAs<LayerImpl>();
+    return MockLayerImpl::Create(tree_impl, layer_id_);
   }
 
   virtual void PushPropertiesTo(LayerImpl* layer_impl) OVERRIDE {