Improve appearance of focus rings at fractional scales.

ui/gfx/canvas.cc

Index: ui/gfx/canvas.cc
diff --git a/ui/gfx/canvas.cc b/ui/gfx/canvas.cc
index ed9cea122815fb411d68469ee87438dfd8ab3131..00e186f0e636edff1d7634cb4488f6aceb33a739 100644
--- a/ui/gfx/canvas.cc
+++ b/ui/gfx/canvas.cc
@@ -373,12 +373,14 @@ void Canvas::DrawFocusRect(const RectF& rect) {
   DrawDashedRect(rect, SK_ColorGRAY);
 }
 
-void Canvas::DrawSolidFocusRect(RectF rect, SkColor color, float thickness) {
+void Canvas::DrawSolidFocusRect(RectF rect, SkColor color, int thickness) {
   cc::PaintFlags flags;
   flags.setColor(color);
-  flags.setStrokeWidth(SkFloatToScalar(thickness));
+  const float adjusted_thickness =
+      std::floor(thickness * image_scale_) / image_scale_;
+  flags.setStrokeWidth(SkFloatToScalar(adjusted_thickness));
   flags.setStyle(cc::PaintFlags::kStroke_Style);
-  rect.Inset(gfx::InsetsF(thickness / 2));
+  rect.Inset(gfx::InsetsF(adjusted_thickness / 2));
   DrawRect(rect, flags);
 }