Remove unused references to NativeTheme in TrayPopupItemStyle.

ash/common/system/date/date_view.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_DATE_DATE_VIEW_H_
 #define ASH_COMMON_SYSTEM_DATE_DATE_VIEW_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 69 matching lines @@
 
   // Updates the format of the displayed time.
   void UpdateTimeFormat();
 
   base::HourClockType GetHourTypeForTesting() const;
 
  private:
   // Sets active rendering state and updates the color of |date_label_|.
   void SetActive(bool active);
 
-  // Updates the style of |date_label_| based on the current native theme.
-  void UpdateStyle();
-
   // BaseDateTimeView:
   void UpdateTextInternal(const base::Time& now) override;
 
   // ActionableView:
   bool PerformAction(const ui::Event& event) override;
 
   // views::View:
   void OnMouseEntered(const ui::MouseEvent& event) override;
   void OnMouseExited(const ui::MouseEvent& event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
-  void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
 
   views::Label* date_label_;
 
   DateAction action_;
 
   DISALLOW_COPY_AND_ASSIGN(DateView);
 };
 
 // Tray view used to display the current time.
 // Exported for tests.
@@ skipping 39 matching lines @@
   std::unique_ptr<views::Label> vertical_label_hours_;
   std::unique_ptr<views::Label> vertical_label_minutes_;
 
   DISALLOW_COPY_AND_ASSIGN(TimeView);
 };
 
 }  // namespace tray
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_DATE_DATE_VIEW_H_