CustomButton: restrict animation repaints to buttons that actually animate

ui/views/controls/button/md_text_button.h

 // Copyright 2015 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_MD_TEXT_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_MD_TEXT_BUTTON_H_
 
 #include <memory>
 
 #include "base/optional.h"
@@ skipping 12 matching lines @@
                                                   const base::string16& text);
   static MdTextButton* Create(ButtonListener* listener,
                               const base::string16& text);
 
   // See |is_prominent_|.
   void SetProminent(bool is_prominent);
 
   // See |bg_color_override_|.
   void SetBgColorOverride(const base::Optional<SkColor>& color);
 
+  // View:
+  void OnPaintBackground(gfx::Canvas* canvas) override;
+
   // LabelButton:
   void OnFocus() override;
   void OnBlur() override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
   std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
   std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
       const override;
   SkColor GetInkDropBaseColor() const override;
   bool ShouldShowInkDropForFocus() const override;
   void SetEnabledTextColors(SkColor color) override;
@@ skipping 18 matching lines @@
 
   // When set, this provides the background color.
   base::Optional<SkColor> bg_color_override_;
 
   DISALLOW_COPY_AND_ASSIGN(MdTextButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_MD_TEXT_BUTTON_H_