Update shelf spacing in Chrome OS according to the MD specs

ash/shelf/shelf_constants.h

 // Copyright 2013 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_SHELF_SHELF_CONSTANTS_H_
 #define ASH_SHELF_SHELF_CONSTANTS_H_
 
 #include "ash/ash_export.h"
 
 namespace ash {
 
+enum ShelfLayoutConstant {
+  // Size of the shelf when visible (height when the shelf is horizontal and
+  // width when the shelf is vertical).
+  SHELF_SIZE,
+
+  // Size of the space between buttons on the shelf.
+  SHELF_BUTTON_SPACING,
+
+  // Size allocated for each button on the shelf.
+  SHELF_BUTTON_SIZE
+};
+
+ASH_EXPORT int GetShelfLayoutConstant(ShelfLayoutConstant constant);
+
 // Invalid image resource id used for ShelfItemDetails.
 extern const int kInvalidImageResourceID;
 
+// We reserve a small area on the edge of the workspace area to ensure that
+// the resize handle at the edge of the window can be hit.
+extern const int kWorkspaceAreaVisibleInset;
+
+// When autohidden we extend the touch hit target onto the screen so that the
+// user can drag the shelf out.
+extern const int kWorkspaceAreaAutoHideInset;
+
+// Size of the shelf when auto-hidden.
+ASH_EXPORT extern const int kAutoHideSize;

[bruthig, 2016/06/03 20:18:17]

|kAutoHideSize| is too general of a variable name to be in the ash namespace
scope.  You could add it to a class or at least make the name more specific.
i.e. kShelfAutoHideSize.  My preference is the former.

[yiyix, 2016/06/10 19:26:04]

This constant is used in both shelf_layout_manager class and
ash_popup_alignment_delegate class. I update the name to kShelfAutoHideSize to
make it more specific.

+
+// Inset between the inner edge of the shelf (towards centre of screen), and
+// the shelf items, notifications, status area etc.
+extern const int kShelfItemInset;
+
 const int kInvalidShelfID = 0;
 
-// Size of the shelf when visible (height when the shelf is horizontal).
-ASH_EXPORT extern const int kShelfSize;
-
-// Size of the space between buttons on the shelf.
-ASH_EXPORT extern const int kShelfButtonSpacing;
-
-// Size allocated for each button on the shelf.
-ASH_EXPORT extern const int kShelfButtonSize;
-
 // The direction of the focus cycling.
 enum CycleDirection {
   CYCLE_FORWARD,
   CYCLE_BACKWARD
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_CONSTANTS_H_