Materialized the font/icon color for some default rows in the system menu.

ash/common/system/tray/tray_item_more.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 ASH_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_
 
+#include <memory>
+
 #include "ash/common/system/tray/actionable_view.h"
 #include "base/macros.h"
 #include "ui/views/view.h"
 
 namespace views {
 class ImageView;
 class Label;
 class View;
 }
 
 namespace ash {
 class SystemTrayItem;
+class TrayPopupItemStyle;
 
-// A view with a chevron ('>') on the right edge. Clicking on the view brings up
+// A view with a more arrow on the right edge. Clicking on the view brings up
 // the detailed view of the tray-item that owns it.
 class TrayItemMore : public ActionableView {
  public:
   TrayItemMore(SystemTrayItem* owner, bool show_more);
   ~TrayItemMore() override;
 
   SystemTrayItem* owner() const { return owner_; }
 
   void SetLabel(const base::string16& label);
   void SetImage(const gfx::ImageSkia& image_skia);
   void SetAccessibleName(const base::string16& name);
 
+ protected:
+  // Returns a style that will be applied to elements in the UpdateStyle()
+  // method. e.g. changing the label's font and color. Descendants can override
+  // to apply specialized configurations of the style. e.g. changing the style's
+  // ColorStyle based on whether Bluetooth is enabled/disabled.
+  virtual std::unique_ptr<TrayPopupItemStyle> CreateStyle() const;
+
+  // Applies the style created from CreateStyle(). Should be called whenever any
+  // input state changes that changes the style configuration created by
+  // CreateStyle(). e.g. if Bluetooth is changed between enabled/disabled then
+  // a differently configured style will be returned from CreateStyle() and thus
+  // it will need to be applied.
+  //
+  // By default this will be called when OnNativeThemeChanged() is called which
+  // will ensure the most up to date theme is actually applied.
+  virtual void UpdateStyle();
+
  private:
-  // TODO(bruthig): Re-design to inform subclasses when the style changes while
-  // avoiding virtual function calls from the constructor.
-  void UpdateStyle();
-
   // Overridden from ActionableView.
   bool PerformAction(const ui::Event& event) override;
 
   // Overridden from views::View.
   void Layout() override;
   void GetAccessibleState(ui::AXViewState* state) override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
 
   SystemTrayItem* owner_;
   // True if |more_| should be shown.
   bool show_more_;
   views::ImageView* icon_;
   views::Label* label_;
   views::ImageView* more_;
   base::string16 accessible_name_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayItemMore);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_