Move condition in CollapsedBorderValue::Width() into constructor

third_party/WebKit/Source/core/layout/CollapsedBorderValue.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 38 matching lines @@
       : color_(0),
         width_(0),
         style_(kBorderStyleNone),
         precedence_(kBorderPrecedenceOff),
         transparent_(false) {}
 
   CollapsedBorderValue(const BorderValue& border,
                        const Color& color,
                        EBorderPrecedence precedence)
       : color_(color),
-        width_(border.NonZero() ? border.Width() : 0),
+        width_(border.Style() > kBorderStyleHidden ? border.Width() : 0),

[Xianzhu, 2017/05/04 20:45:26]

BorderValue::NonZero() is:
 { return Width() && (style_ != kBorderStyleNone); }

width_ was and will be set to:
                               old code         new code
border.Width()==0                 0                0
Style()==kBorderStyleNone         0                0
Style()==kBorderStyleHidden    border.Width()      0

For both old code and new code, CollapsedBorderValue::Width() returns 0 in the
above cases, or otherwise the original border width.

[wkorman, 2017/05/04 21:13:04]

Seems like unit tests for these permutations could be helpful for future. It is
mainly a simple container class but there is some logic here and the class is
referenced by both LayoutTableCell and TableSectionPainter.

[Xianzhu, 2017/05/04 22:23:35]

Added tests.

         style_(border.Style()),
         precedence_(precedence),
         transparent_(border.IsTransparent()) {
     DCHECK(precedence != kBorderPrecedenceOff);
   }
 
-  unsigned Width() const { return style_ > kBorderStyleHidden ? width_ : 0; }
+  unsigned Width() const { return width_; }
   EBorderStyle Style() const { return static_cast<EBorderStyle>(style_); }
   bool Exists() const { return precedence_ != kBorderPrecedenceOff; }
   Color GetColor() const { return color_; }
   bool IsTransparent() const { return transparent_; }
   EBorderPrecedence Precedence() const {
     return static_cast<EBorderPrecedence>(precedence_);
   }
 
   bool IsSameIgnoringColor(const CollapsedBorderValue& o) const {
     return Width() == o.Width() && Style() == o.Style() &&
@@ skipping 18 matching lines @@
   Color color_;
   unsigned width_ : 24;
   unsigned style_ : 4;       // EBorderStyle
   unsigned precedence_ : 3;  // EBorderPrecedence
   unsigned transparent_ : 1;
 };
 
 }  // namespace blink
 
 #endif  // CollapsedBorderValue_h