MD - update checkbox and radio buttons

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 <stddef.h>
 
 #include <utility>
 
@@ skipping 98 matching lines @@
 
   // Inset the button focus rect from the actual border; roughly match Windows.
   if (!ui::MaterialDesignController::IsModeMaterial()) {
     SetFocusPainter(Painter::CreateDashedFocusPainterWithInsets(gfx::Insets(
         kFocusRectInset, kFocusRectInset, kFocusRectInset, kFocusRectInset)));
   }
 }
 
 LabelButton::~LabelButton() {}
 
-const gfx::ImageSkia& LabelButton::GetImage(ButtonState for_state) {
+gfx::ImageSkia LabelButton::GetImage(ButtonState for_state) const {
   if (for_state != STATE_NORMAL && button_state_images_[for_state].isNull())
     return button_state_images_[STATE_NORMAL];
   return button_state_images_[for_state];
 }
 
 void LabelButton::SetImage(ButtonState for_state, const gfx::ImageSkia& image) {
   button_state_images_[for_state] = image;
   UpdateImage();
 }
 
@@ skipping 441 matching lines @@
 void LabelButton::ResetLabelEnabledColor() {
   const SkColor color =
       explicitly_set_colors_[state()]
           ? button_state_colors_[state()]
           : PlatformStyle::TextColorForButton(button_state_colors_, *this);
   if (state() != STATE_DISABLED && label_->enabled_color() != color)
     label_->SetEnabledColor(color);
 }
 
 }  // namespace views