Added common layout framework for system menu rows.

ash/common/system/tray/tray_constants.cc

Index: ash/common/system/tray/tray_constants.cc
diff --git a/ash/common/system/tray/tray_constants.cc b/ash/common/system/tray/tray_constants.cc
index 11923f03d1e071e938c11be1b08c5dffceec604f..9e20caa1da71ccccb5c5a0ed705d224ead5c8139 100644
--- a/ash/common/system/tray/tray_constants.cc
+++ b/ash/common/system/tray/tray_constants.cc
@@ -96,6 +96,14 @@ int GetTrayConstant(TrayConstant constant) {
   const int kTraySpacing[] = {4, 4, 0};
   const int kTrayPaddingFromEdgeOfShelf[] = {3, 3, 4};
   const int kTrayPopupItemHeight[] = {46, 46, 48};
+  // TODO(bruthig): Use the correct values for non-material design.
+  const int kTrayPopupItemLeftInset[] = {0, 0, 4};
+  // TODO(bruthig): Use the correct values for non-material design.
+  const int kTrayPopupItemRightInset[] = {0, 0, 4};
+  // TODO(bruthig): Use the correct values for non-material design.
+  const int kTrayPopupItemMinStartWidth[] = {48, 48, 48};
+  // TODO(bruthig): Use the correct values for non-material design.
+  const int kTrayPopupItemMinEndWidth[] = {48, 48, 48};
   const int kVirtualKeyboardButtonSize[] = {39, 39, kTrayItemSize};
   const int kTrayImeMenuIcon[] = {40, 40, kTrayItemSize};
   const int kTrayImageItemPadding[] = {1, 1, 3};
@@ -113,6 +121,14 @@ int GetTrayConstant(TrayConstant constant) {
       return kTrayPaddingFromEdgeOfShelf[mode];
     case TRAY_POPUP_ITEM_HEIGHT:
       return kTrayPopupItemHeight[mode];
+    case TRAY_POPUP_ITEM_LEFT_INSET:
+      return kTrayPopupItemLeftInset[mode];
+    case TRAY_POPUP_ITEM_RIGHT_INSET:
+      return kTrayPopupItemRightInset[mode];
+    case TRAY_POPUP_ITEM_MIN_START_WIDTH:
+      return kTrayPopupItemMinStartWidth[mode];
+    case TRAY_POPUP_ITEM_MIN_END_WIDTH:
+      return kTrayPopupItemMinEndWidth[mode];
     case VIRTUAL_KEYBOARD_BUTTON_SIZE:
       return kVirtualKeyboardButtonSize[mode];
     case TRAY_IME_MENU_ICON: