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

ash/common/system/tray/tray_item_more.h

Index: ash/common/system/tray/tray_item_more.h
diff --git a/ash/common/system/tray/tray_item_more.h b/ash/common/system/tray/tray_item_more.h
index acd9b30a6b729354140f07d94da14388b5ba2347..0c9bac5cedc07be1874dc87af6637465c9bcb441 100644
--- a/ash/common/system/tray/tray_item_more.h
+++ b/ash/common/system/tray/tray_item_more.h
@@ -5,6 +5,8 @@
 #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"
@@ -17,8 +19,9 @@ 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:
@@ -31,11 +34,24 @@ class TrayItemMore : public ActionableView {
   void SetImage(const gfx::ImageSkia& image_skia);
   void SetAccessibleName(const base::string16& name);
 
- private:
-  // TODO(bruthig): Re-design to inform subclasses when the style changes while
-  // avoiding virtual function calls from the constructor.
-  void UpdateStyle();
+ 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:
   // Overridden from ActionableView.
   bool PerformAction(const ui::Event& event) override;