Use LayoutUnit for all border-*-width logic

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

Index: third_party/WebKit/Source/core/style/BorderWidth.h
diff --git a/third_party/WebKit/Source/core/style/BorderWidth.h b/third_party/WebKit/Source/core/style/BorderWidth.h
new file mode 100644
index 0000000000000000000000000000000000000000..274d192b6df3282ef9d925da9f0abafc08fb7fe0
--- /dev/null
+++ b/third_party/WebKit/Source/core/style/BorderWidth.h
@@ -0,0 +1,48 @@
+// 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();
+  friend class ComputedStyle;

[shend, 2017/05/23 08:05:32]

does this need to be a friend?

[nainar, 2017/05/23 08:10:04]

nope artifact of BorderValue which I blatantly copied. 

+
+ 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;
+  }
+  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_;
+  }
+
+ protected:

[shend, 2017/05/23 08:05:32]

I would just do private.

[nainar, 2017/05/23 08:10:04]

Done.

+  static unsigned WidthToFixedPoint(float width) {
+    DCHECK_GE(width, 0);
+    return static_cast<unsigned>(std::min<float>(width, kMaxForBorderWidth) *
+                                 kBorderWidthDenominator);
+  }
+
+  unsigned width_ : 26;  // Fixed point width

[shend, 2017/05/23 08:05:32]

there's probably no need to bit pack this anymore, since BorderWidth is not bit
packed in ComputedStyle.

[nainar, 2017/05/23 08:10:04]

Yup. Done

+};
+
+}  // namespace blink
+
+#endif  // BorderWidth_h