cc: Clean up iterator template to only take 1 parameter.

cc/trees/occlusion_tracker_perftest.cc

Index: cc/trees/occlusion_tracker_perftest.cc
diff --git a/cc/trees/occlusion_tracker_perftest.cc b/cc/trees/occlusion_tracker_perftest.cc
index 8c865f73d1ff436ab2d931eed5fc6135f756a0a9..62c4bbcc706e01b99c0ffd94617ade296a070d9f 100644
--- a/cc/trees/occlusion_tracker_perftest.cc
+++ b/cc/trees/occlusion_tracker_perftest.cc
@@ -89,12 +89,8 @@ TEST_F(OcclusionTrackerPerfTest, UnoccludedContentRect_FullyOccluded) {
   ASSERT_EQ(1u, rsll.size());
   EXPECT_EQ(1u, rsll[0]->render_surface()->layer_list().size());
 
-  typedef LayerIterator<LayerImpl,
-                        LayerImpl::LayerListType,
-                        LayerImpl::RenderSurfaceType,
-                        LayerIteratorActions::FrontToBack> IteratorType;
-  IteratorType begin = IteratorType::Begin(&rsll);
-  IteratorType end = IteratorType::End(&rsll);
+  LayerIterator<LayerImpl> begin = LayerIterator<LayerImpl>::Begin(&rsll);
+  LayerIterator<LayerImpl> end = LayerIterator<LayerImpl>::End(&rsll);
 
   LayerIteratorPosition<LayerImpl> pos = begin;