Update shelf spacing in Chrome OS according to the MD specs

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 f6c9c16e1a61bdb604ee67dad85f59e69b9da496..c9643b143a2de013f63f5dabf9eaea65cb0837fc 100644
--- a/ash/common/system/tray/tray_constants.h
+++ b/ash/common/system/tray/tray_constants.h
@@ -22,7 +22,15 @@ extern const int kBubblePaddingHorizontalSide;
 extern const int kBubblePaddingVerticalBottom;
 extern const int kBubblePaddingVerticalSide;
 
-extern const int kPaddingFromEdgeOfShelf;
+extern const int kAdjustBackgroundPadding;
+enum TrayConstant {

[James Cook, 2016/06/13 21:43:15]

nit: blank line above

Also, I would move this down to just above GetTrayConstant() on line 91.

[yiyix, 2016/06/14 05:55:26]

Done.

+  // Padding between items in the status tray area.
+  TRAY_SPACING,
+
+  // Padding between the edge of shelf and the item in status tray area.
+  PADDING_FROM_EDGE_OF_SHELF,

[James Cook, 2016/06/13 21:43:15]

If you're going to use a regular enum, please call this TRAY_PADDING_... so we
know it's for the tray. Or you could switch to "enum class TrayConstant" and use
TrayConstant::SPACING and TrayConstant::PADDING_FROM_EDGE_OF_SHELF.

[yiyix, 2016/06/14 05:55:26]

I updated the variable name to TRAY_PADDING_FROM_EDGE_OF_SHELF

+};
+
 extern const int kTrayBubbleAnchorTopInsetBottomAnchor;
 
 extern const int kTrayImageItemHorizontalPaddingBottomAlignment;
@@ -76,8 +84,11 @@ extern const int kTrayNotificationContentsWidth;
 extern const int kTrayAvatarCornerRadius;
 extern const int kTrayAvatarSize;
 
-extern const int kTraySpacing;
+extern const int kMessageCenterBubblePadding;
 extern const int kShelfItemHeight;
+extern const int kShelfItemSizeMD;

[James Cook, 2016/06/13 21:43:16]

Is this the MD version of the line above? If so, I would either call both of
them Height or both Size.

If they are different, I would leave a comment explaining how/why.

[yiyix, 2016/06/14 05:55:26]

All tray background are sized 32 by 32 in Chrome OS MD. However, The backgrounds
are not sized properly now, so I cannot add this variable to the GetTrayConstant
function yet. I use this value when it makes sense in the code. I added a TODO
in the code.

+
+int GetTrayConstant(TrayConstant constant);
 
 namespace test {
 const int kSettingsTrayItemViewId = 10000;