Reland of "Added common layout framework for system menu rows."

ash/common/system/tray/tray_constants.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_CONSTANTS_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_CONSTANTS_H_
 
 #include "ash/ash_export.h"
 
 typedef unsigned int SkColor;
@@ skipping 97 matching lines @@
 
   // Padding between items in the status tray area.
   TRAY_SPACING,
 
   // Padding between the edge of shelf and the item in status tray area.
   TRAY_PADDING_FROM_EDGE_OF_SHELF,
 
   // The height of the rows in the system tray menu.
   TRAY_POPUP_ITEM_HEIGHT,
 
+  // The left inset for all tray system menu rows.
+  TRAY_POPUP_ITEM_LEFT_INSET,
+
+  // The right inset for all tray system menu rows.
+  TRAY_POPUP_ITEM_RIGHT_INSET,
+
+  // The minimum default width for the left container of the system menu rows.
+  TRAY_POPUP_ITEM_MIN_START_WIDTH,
+
+  // The minimum default width for the right container of the system menu rows.
+  TRAY_POPUP_ITEM_MIN_END_WIDTH,
+
   // The width and height of the virtual keyboard button in the status tray
   // area. For non-MD, adjustments are made to the button dimensions based on
   // the shelf orientation, so this constant does not specify the true
   // user-visible button bounds.
   VIRTUAL_KEYBOARD_BUTTON_SIZE,
 
   // The icon size of opt-in IME menu tray.
   TRAY_IME_MENU_ICON,
 
   // Extra padding used beside a single icon in the tray area of the shelf.
   TRAY_IMAGE_ITEM_PADDING,
 };
 
 int GetTrayConstant(TrayConstant constant);
 
 namespace test {
 const int kSettingsTrayItemViewId = 10000;
 const int kAccessibilityTrayItemViewId = 10001;
 }  // namespace test
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_CONSTANTS_H_