[Chrome OS MD] Implement accessibility detailed view for the MD Ash system menu

ash/common/system/tray/tray_constants.h

Index: ash/common/system/tray/tray_constants.h
diff --git a/ash/common/system/tray/tray_constants.h b/ash/common/system/tray/tray_constants.h
index b9d3a32af79e21e088847e920ffa694aa524518a..8a31f47c084d01aa946983dfc1f0cb5e6296fec3 100644
--- a/ash/common/system/tray/tray_constants.h
+++ b/ash/common/system/tray/tray_constants.h
@@ -97,6 +97,12 @@ extern const SkColor kTrayIconColor;
 extern const int kMenuIconSize;
 extern const SkColor kMenuIconColor;
 
+// The margin between the menu and the icon in system menu.

[tdanderson, 2016/09/19 23:32:27]

I would suggest wording as "The margin between the edge of the menu and the edge
of the button" or similar since the spacing from the menu edge to the icon
itself would actually be 4 + 14.

[yiyix, 2016/09/21 17:10:48]

Done.

+extern const int kMenuIconMargin;
+
+// The space reserved to display menu icons in detailed view page.

[tdanderson, 2016/09/19 23:32:27]

Suggested wording: "The size of buttons in the system menu."

[yiyix, 2016/09/21 17:10:47]

Done.

+extern const int kMenuButtonSize;
+
 enum TrayConstant {
   // A legacy height value used in non-MD calculations for applying additional
   // borders on tray items.