[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..3e5ce916b61898f7e8f21d42fdbe445651d1d5e9 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.
+extern const int kMenuIconMargin;
+
+// Padding around icons in system menu.
+extern const int kIconPadding;

[tdanderson, 2016/09/15 16:13:26]

Perhaps introduce a constant for the size of the buttons in the MD system menu
(say, kMenuButtonSize = 48) and then deriving the padding value using
kMenuButtonSize and the size of the icon.

Note also that you're repeating some constants introduced in
common_palette_tool. Now would be a good opportunity to have common_palette_tool
and tray_accessibility both use the same set of constants.

[yiyix, 2016/09/19 20:24:55]

I like the idea of using 48, as the design changes in the future, we don't need
to update this constant.

Do you mean that I have introduced kMenuIconMargin again in this file because
the variable kExtraMarginFromLeftEdge = 4 is also introduced in
common_palette_tool? I can make common_palette_tool to use this one instead. I
think this variable will be used in other detailed view rows as well.

I also found that kIconSize is introduced in both common_palette_tool and
palette_tray and which again defined as kMenuIconSize in tray_constants.i can
unify that variable too.

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