Rewrite scoped_ptr<T>(NULL) to use the default ctor in cc/.

cc/trees/tree_synchronizer_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 "cc/trees/tree_synchronizer.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "cc/animation/layer_animation_controller.h"
@@ skipping 465 matching lines @@
       TreeSynchronizer::SynchronizeTrees(layer_tree_root.get(),
                                          layer_impl_tree_root.Pass(),
                                          host_impl_.active_tree());
   ExpectTreesAreIdentical(layer_tree_root.get(),
                           layer_impl_tree_root.get(),
                           host_impl_.active_tree());
 }
 
 TEST_F(TreeSynchronizerTest, SynchronizeAnimations) {
   LayerTreeSettings settings;
-  FakeProxy proxy(scoped_ptr<Thread>(NULL));
+  FakeProxy proxy((scoped_ptr<Thread>()));
   DebugScopedSetImplThread impl(&proxy);
   FakeRenderingStatsInstrumentation stats_instrumentation;
   scoped_ptr<LayerTreeHostImpl> host_impl =
       LayerTreeHostImpl::Create(settings,
                                 NULL,
                                 &proxy,
                                 &stats_instrumentation);
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
 
@@ skipping 13 matching lines @@
       TreeSynchronizer::SynchronizeTrees(layer_tree_root.get(),
                                          layer_impl_tree_root.Pass(),
                                          host_impl_.active_tree());
 
   EXPECT_TRUE(static_cast<FakeLayerAnimationController*>(
       layer_tree_root->layer_animation_controller())->SynchronizedAnimations());
 }
 
 }  // namespace
 }  // namespace cc