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

ash/display/screen_position_controller_unittest.cc

 // Copyright (c) 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 "ash/display/screen_position_controller.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/shell_test_api.h"
@@ skipping 29 matching lines @@
   display_controller->SetLayoutForCurrentDisplays(layout);
 }
 
 internal::ScreenPositionController* GetScreenPositionController() {
   ShellTestApi test_api(Shell::GetInstance());
   return test_api.screen_position_controller();
 }
 
 class ScreenPositionControllerTest : public test::AshTestBase {
  public:
-  ScreenPositionControllerTest() : window_(NULL) {}
+  ScreenPositionControllerTest() {}
   virtual ~ScreenPositionControllerTest() {}
 
   virtual void SetUp() OVERRIDE {
     AshTestBase::SetUp();
     window_.reset(new aura::Window(&window_delegate_));
     window_->SetType(aura::client::WINDOW_TYPE_NORMAL);
     window_->Init(ui::LAYER_NOT_DRAWN);
     SetDefaultParentByPrimaryRootWindow(window_.get());
     window_->set_id(1);
   }
@@ skipping 203 matching lines @@
   EXPECT_EQ("210,70", ConvertHostPointToScreen(60, 70));
   // The point is out of the host windows.
   EXPECT_EQ("210,-50", ConvertHostPointToScreen(60, -50));
   // The point is on the 2nd host. Point on 1nd host (60, 60)
   // 1/2 * 1.5 = (45,45)
   EXPECT_EQ("45,45", ConvertHostPointToScreen(60, -340));
 }
 
 }  // namespace test
 }  // namespace ash