Material Design: Fix MdLabelButton not updating text colors on theme changes

ui/views/controls/button/label_button.h

 // 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.
 
 #ifndef UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 96 matching lines @@
   std::unique_ptr<InkDropHighlight> CreateInkDropHighlight() const override;
 
  protected:
   ImageView* image() const { return image_; }
   Label* label() const { return label_; }
 
   bool explicitly_set_normal_color() const {
     return explicitly_set_colors_[STATE_NORMAL];
   }
 
+  void ResetExplicitnessOfEnabledTextColors();
+
   // Returns the available area for the label and image. Subclasses can change
   // these bounds if they need room to do manual painting.
   virtual gfx::Rect GetChildAreaBounds();
 
   // Sets the font list used by this button.
   virtual void SetFontList(const gfx::FontList& font_list);
 
   // View:
   void OnPaint(gfx::Canvas* canvas) override;
   void OnFocus() override;
@@ skipping 109 matching lines @@
   gfx::HorizontalAlignment horizontal_alignment_;
 
   std::unique_ptr<Painter> focus_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(LabelButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_