Add presubmit check for scoped_ptr usage.

ui/views/controls/button/label_button.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 "ui/views/controls/button/label_button.h"
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "ui/gfx/animation/throb_animation.h"
 #include "ui/gfx/canvas.h"
@@ skipping 173 matching lines @@
   if (style_ == STYLE_BUTTON) {
     label_->SetFontList(
         is_default ? cached_bold_font_list_ : cached_normal_font_list_);
   }
 }
 
 void LabelButton::SetStyle(ButtonStyle style) {
   style_ = style;
   // Inset the button focus rect from the actual border; roughly match Windows.
   if (style == STYLE_BUTTON) {
-    SetFocusPainter(scoped_ptr<Painter>());
+    SetFocusPainter(nullptr);
   } else {
     SetFocusPainter(Painter::CreateDashedFocusPainterWithInsets(
                         gfx::Insets(3, 3, 3, 3)));
   }
   if (style == STYLE_BUTTON) {
     label_->SetHorizontalAlignment(gfx::ALIGN_CENTER);
     SetFocusable(true);
   }
   if (style == STYLE_BUTTON)
     SetMinSize(gfx::Size(70, 33));
@@ skipping 304 matching lines @@
   GetExtraParams(params);
   return ui::NativeTheme::kHovered;
 }
 
 void LabelButton::ResetCachedPreferredSize() {
   cached_preferred_size_valid_ = false;
   cached_preferred_size_= gfx::Size();
 }
 
 }  // namespace views