Update shelf spacing in Chrome OS according to the MD specs

ash/system/tray/system_tray.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_TRAY_SYSTEM_TRAY_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 139 matching lines @@
 
   // Get the tray item view (or NULL) for a given |tray_item| in a unit test.
   views::View* GetTrayItemViewForTest(SystemTrayItem* tray_item);
 
   // Gets tray_cast_ for browser tests.
   TrayCast* GetTrayCastForTesting() const;
 
   // Gets tray_date_ for browser tests.
   TrayDate* GetTrayDateForTesting() const;
 
+  void GetHitRegionInsets(gfx::Insets& insets) override;
+
  private:
   // Creates the default set of items for the sytem tray.
   void CreateItems(SystemTrayDelegate* delegate);
 
   // Resets |system_bubble_| and clears any related state.
   void DestroySystemBubble();
 
   // Resets |notification_bubble_| and clears any related state.
   void DestroyNotificationBubble();
 
@@ skipping 76 matching lines @@
   // A reference to the Screen share and capture item.
   ScreenTrayItem* screen_capture_tray_item_;  // not owned
   ScreenTrayItem* screen_share_tray_item_;  // not owned
 
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_