Fix appearance of header row separators in table view at fractional

ui/gfx/canvas.cc

Index: ui/gfx/canvas.cc
diff --git a/ui/gfx/canvas.cc b/ui/gfx/canvas.cc
index 43d799716b479999dc736c5aed223e47428c5811..c83118749e7f2d904f44a582202b6b7d7819d3b1 100644
--- a/ui/gfx/canvas.cc
+++ b/ui/gfx/canvas.cc
@@ -321,6 +321,22 @@ void Canvas::DrawLine(const PointF& p1,
                     SkFloatToScalar(p2.x()), SkFloatToScalar(p2.y()), flags);
 }
 
+void Canvas::DrawSharpLine(const PointF& p1, const PointF& p2, SkColor color) {
+  ScopedCanvas scoped(this);
+  float dsf = UndoDeviceScaleFactor();
+
+  PointF start = p1;

[Peter Kasting, 2017/02/15 00:43:59]

Nit: If you're just going to copy these anyway, I suggest passing them to the
function by value and then scaling the args directly.  This lets the compiler be
more efficient in some cases (when caller structs don't have to be forced to the
stack).

[Evan Stade, 2017/02/15 16:54:46]

I thought we never passed non-PODs by value and coverity at least used to
complain about that. Anyway I changed this and one other function in this file.

+  start.Scale(dsf);
+  PointF end = p2;
+  end.Scale(dsf);
+
+  cc::PaintFlags flags;
+  flags.setColor(color);
+  flags.setStrokeWidth(std::floor(dsf));

[Evan Stade, 2017/02/14 23:06:03]

I guess I could use gfx::ToFlooredInt for this, but what's wrong with
std::floor?

[Peter Kasting, 2017/02/15 00:43:59]

floor() returns a float, which is potentially outside the representable range
for an int (and also isn't an int typewise).

In this case, you're trying to convert back to a floating-point type anyway, so
I'd do SkFloatToScalar(std::floor()) instead of trying to go through
ToFlooredInt.

[Evan Stade, 2017/02/15 16:54:46]

Done.

+
+  DrawLine(start, end, flags);
+}
+
 void Canvas::DrawCircle(const Point& center_point,
                         int radius,
                         const cc::PaintFlags& flags) {