Use LayoutUnit for all border-*-width logic

third_party/WebKit/Source/core/style/BorderWidth.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BorderWidth_h
+#define BorderWidth_h
+
+#include "core/style/ComputedStyleConstants.h"
+
+namespace blink {
+
+class BorderWidth {
+  DISALLOW_NEW();
+
+ public:
+  BorderWidth() { SetWidth(3); }
+
+  BorderWidth(float width) { SetWidth(width); }
+
+  bool operator==(const BorderWidth& o) const { return width_ == o.width_; }
+
+  bool operator!=(const BorderWidth& o) const { return !(*this == o); }
+
+  float Width() const {
+    return static_cast<float>(width_) / kBorderWidthDenominator;

[alancutter (OOO until 2018), 2017/05/24 01:50:06]

I wonder why we don't use LayoutUnit for this. It has the same fixed point
denominator.

[nainar1, 2017/05/24 01:53:21]

Could use LayoutUnit - didn't know it was a thing. shend@, WDYT?

[shend, 2017/05/24 01:55:08]

If it does the same thing and you could get it to work, then sure!

+  }
+  void SetWidth(float width) { width_ = WidthToFixedPoint(width); }
+
+  // Since precision is lost with fixed point, comparisons also have
+  // to be done in fixed point.
+  bool WidthEquals(float width) const {
+    return WidthToFixedPoint(width) == width_;
+  }
+
+ private:
+  static unsigned WidthToFixedPoint(float width) {
+    DCHECK_GE(width, 0);
+    return static_cast<unsigned>(std::min<float>(width, kMaxForBorderWidth) *
+                                 kBorderWidthDenominator);
+  }
+
+  unsigned width_;  // Fixed point width
+};
+
+}  // namespace blink
+
+#endif  // BorderWidth_h