Split StyleSurroundData::padding into four individual Lengths.

third_party/WebKit/Source/platform/Theme.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 27 matching lines @@
     case kCheckboxPart:
     case kRadioPart:
       return LengthBox(0);
     default:
       return zoomed_box;
   }
 }
 
 LengthBox Theme::ControlPadding(ControlPart part,
                                 const FontDescription&,
-                                const LengthBox& zoomed_box,
+                                const Length& zoomed_box_top,
+                                const Length& zoomed_box_right,
+                                const Length& zoomed_box_bottom,
+                                const Length& zoomed_box_left,
                                 float) const {
   switch (part) {
     case kMenulistPart:
     case kMenulistButtonPart:
     case kCheckboxPart:
     case kRadioPart:
       return LengthBox(0);
     default:
-      return zoomed_box;
+      return LengthBox(zoomed_box_top, zoomed_box_right, zoomed_box_bottom,

[shend, 2017/04/20 07:07:20]

Does this get called often? If so, there might be a cost of copy and
constructing the LengthBox.

[nainar, 2017/04/20 07:13:09]

Yes, it gets called up through StyleResolver::StyleForElement()

[shend, 2017/04/20 07:20:56]

That's annoying. Maybe ask alancutter@ for advice on how to prevent the cost of
constructing a LengthBox?

[nainar, 2017/04/21 00:15:19]

Adding him for owners and asking his opinion on the matter. 

[alancutter (OOO until 2018), 2017/04/21 03:13:32]

It was doing a copy anyway, I wouldn't worry about it.

+                       zoomed_box_left);
   }
 }
 
 }  // namespace blink