Make normal MD text buttons *on infobars* white.

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"
 #include "ui/views/controls/button/label_button.h"
 
 namespace views {
 
 namespace internal {
 class MdFocusRing;
 }  // namespace internal
 
 // A button class that implements the Material Design text button spec.
 class VIEWS_EXPORT MdTextButton : public LabelButton {
@@ skipping 11 matching lines @@
   static MdTextButton* CreateMdButton(ButtonListener* listener,
                                       const base::string16& text);
 
   // Paint an MD-style focus ring on the given canvas at the given bounds.
   static void PaintMdFocusRing(gfx::Canvas* canvas,
                                View* view,
                                int thickness,
                                SkAlpha alpha);
 
   void SetCallToAction(bool cta);
+  void set_bg_color_override(SkColor color) { bg_color_override_ = color; }
 
   // LabelButton:
   void Layout() override;
   void OnFocus() override;
   void OnBlur() override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
   std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
       const override;
   SkColor GetInkDropBaseColor() const override;
   bool ShouldShowInkDropForFocus() const override;
   void SetEnabledTextColors(SkColor color) override;
   void UpdateStyleToIndicateDefaultStatus() override;
 
  private:
   MdTextButton(ButtonListener* listener);
   ~MdTextButton() override;
 
   void UpdateColors();
 
   // The MD-style focus ring. This is not done via a FocusPainter
   // because it needs to paint to a layer so it can extend beyond the bounds of
   // |this|.
   internal::MdFocusRing* focus_ring_;
 
   // True if this button uses call-to-action styling.
   bool is_cta_;
 
+  // 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_