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

cc/layers/scrollbar_layer_unittest.cc

 // Copyright 2012 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/layers/scrollbar_layer.h"
 
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/layers/append_quads_data.h"
 #include "cc/layers/scrollbar_layer_impl.h"
 #include "cc/quads/solid_color_draw_quad.h"
@@ skipping 402 matching lines @@
   context->getIntegerv(GL_MAX_TEXTURE_SIZE, &max_size);
   SetScrollbarBounds(gfx::Size(max_size + 100, max_size + 100));
   RunTest(true, true, true);
 }
 
 class MockLayerTreeHost : public LayerTreeHost {
  public:
   MockLayerTreeHost(LayerTreeHostClient* client,
                     const LayerTreeSettings& settings)
       : LayerTreeHost(client, settings) {
-      Initialize(scoped_ptr<Thread>(NULL));
+    Initialize(scoped_ptr<Thread>());
   }
 };
 
 
 class ScrollbarLayerTestResourceCreation : public testing::Test {
  public:
   ScrollbarLayerTestResourceCreation()
       : fake_client_(FakeLayerTreeHostClient::DIRECT_3D) {}
 
   void TestResourceUpload(size_t expected_resources) {
@@ skipping 142 matching lines @@
 
 TEST_F(ScaledScrollbarLayerTestResourceCreation, ScaledResourceUpload) {
   layer_tree_settings_.solid_color_scrollbars = false;
   // Pick a test scale that moves the scrollbar's (non-zero) position to
   // a non-pixel-aligned location.
   TestResourceUpload(2, 1.41f);
 }
 
 }  // namespace
 }  // namespace cc