Stop using shell::GetInstance()->system_tray() in system tray items

ash/system/drive/tray_drive.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_SYSTEM_DRIVE_TRAY_DRIVE_H_
 #define ASH_SYSTEM_DRIVE_TRAY_DRIVE_H_
 
 #include "ash/system/drive/drive_observer.h"
 #include "ash/system/tray/tray_image_item.h"
 
 namespace views {
 class Label;
 }
 
 namespace ash {
-
 namespace internal {
 
 namespace tray {
 class DriveTrayView;
 class DriveDefaultView;
 class DriveDetailedView;
 }
 
 class TrayDrive : public TrayImageItem,
                   public DriveObserver {
  public:
-  TrayDrive();
+  explicit TrayDrive(SystemTray* system_tray);
   virtual ~TrayDrive();
 
  private:
   // Overridden from TrayImageItem.
   virtual bool GetInitialVisibility() OVERRIDE;
 
   // Overridden from SystemTrayItem.
   virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
   virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
@@ skipping 11 matching lines @@
   tray::DriveDefaultView* default_;
   tray::DriveDetailedView* detailed_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayDrive);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_DRIVE_TRAY_DRIVE_H_