Apply View::set_preferred_size in some more places.

ash/system/tray/tray_constants.h

Index: ash/system/tray/tray_constants.h
diff --git a/ash/system/tray/tray_constants.h b/ash/system/tray/tray_constants.h
index c3c20cbc8e6f60b6fe409da9e5c8e89d8e2fd2b0..620cfecd96e34f7c8601cd141b0043632da8eb63 100644
--- a/ash/system/tray/tray_constants.h
+++ b/ash/system/tray/tray_constants.h
@@ -33,7 +33,7 @@ extern const int kTrayImageItemHorizontalPaddingVerticalAlignment;
 ASH_EXPORT extern const int kTrayItemSize;
 
 // Extra padding used beside a single icon in the tray area of the shelf.
-extern const int kTrayImageItemPadding;
+constexpr int kTrayImageItemPadding = 3;
 
 extern const int kTrayLabelItemHorizontalPaddingBottomAlignment;
 extern const int kTrayLabelItemVerticalPaddingVerticalAlignment;
@@ -106,7 +106,7 @@ extern const SkColor kTrayIconColor;
 
 // The total visual padding at the start and end of the icon/label section
 // of the tray.
-extern const int kTrayEdgePadding;
+constexpr int kTrayEdgePadding = 6;
 
 // The size and foreground color of the icons appearing in the material design
 // system menu.