Move views::Label DisabledColor logic into views::LabelButtonLabel

ui/views/controls/button/label_button.h

Index: ui/views/controls/button/label_button.h
diff --git a/ui/views/controls/button/label_button.h b/ui/views/controls/button/label_button.h
index 5d61e32cbf9c79a9c4ba161fff989a524fd3b465..0fb03378c74bca784ea7d4ba51c12eec45d8aa29 100644
--- a/ui/views/controls/button/label_button.h
+++ b/ui/views/controls/button/label_button.h
@@ -23,6 +23,7 @@ namespace views {
 
 class InkDropContainerView;
 class LabelButtonBorder;
+class LabelButtonLabel;
 
 // LabelButton is a button with text and an icon, it's not focusable by default.
 class VIEWS_EXPORT LabelButton : public CustomButton,
@@ -107,7 +108,7 @@ class VIEWS_EXPORT LabelButton : public CustomButton,
 
  protected:
   ImageView* image() const { return image_; }
-  Label* label() const { return label_; }
+  Label* label() const;
   InkDropContainerView* ink_drop_container() const {
     return ink_drop_container_;
   }
@@ -186,7 +187,7 @@ class VIEWS_EXPORT LabelButton : public CustomButton,
 
   // The image and label shown in the button.
   ImageView* image_;
-  Label* label_;
+  LabelButtonLabel* label_;
 
   // A separate view is necessary to hold the ink drop layer so that it can
   // be stacked below |image_| and on top of |label_|, without resorting to