MD - update checkbox and radio buttons

ui/views/controls/button/label_button.cc

Index: ui/views/controls/button/label_button.cc
diff --git a/ui/views/controls/button/label_button.cc b/ui/views/controls/button/label_button.cc
index 8c13cf00079a77fd6f6a80664e590b9e06a842af..a3fe0b74a23aaf8f4064158d164914f5e7159037 100644
--- a/ui/views/controls/button/label_button.cc
+++ b/ui/views/controls/button/label_button.cc
@@ -116,7 +116,7 @@ LabelButton::LabelButton(ButtonListener* listener, const base::string16& text)
 
 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];