Pass scroll bar placement as an enum instead of std::string

Source/platform/scroll/ScrollTypes.h

 /*
  * Copyright (C) 2006 Apple Computer, 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 151 matching lines @@
     BackTrackPart = 1 << 2,
     ThumbPart = 1 << 3,
     ForwardTrackPart = 1 << 4,
     BackButtonEndPart = 1 << 5,
     ForwardButtonEndPart = 1 << 6,
     ScrollbarBGPart = 1 << 7,
     TrackBGPart = 1 << 8,
     AllParts = 0xffffffff
 };
 
-enum ScrollbarButtonsPlacement {
-    ScrollbarButtonsNone,
-    ScrollbarButtonsSingle,
-    ScrollbarButtonsDoubleStart,
-    ScrollbarButtonsDoubleEnd,
-    ScrollbarButtonsDoubleBoth
-};
-
 enum ScrollbarOverlayStyle {
     ScrollbarOverlayStyleDefault,
     ScrollbarOverlayStyleDark,
     ScrollbarOverlayStyleLight
 };
 
 // The result of an attempt to scroll. If didScroll is true, then unusedScrollDelta gives
 // the amount of the scroll delta that was not consumed by scrolling. If didScroll is false
 // then unusedScrollDelta is zero.
 struct ScrollResultOneDimensional {
@@ skipping 26 matching lines @@
     bool didScrollY;
     float unusedScrollDeltaX;
     float unusedScrollDeltaY;
 };
 
 typedef unsigned ScrollbarControlPartMask;
 
 }
 
 #endif