Improve appearance of focus rings at fractional scales.

ui/gfx/canvas.cc

 // Copyright (c) 2012 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.
 
 #include "ui/gfx/canvas.h"
 
 #include <cmath>
 #include <limits>
 
 #include "base/i18n/rtl.h"
@@ skipping 355 matching lines @@
 }
 
 void Canvas::DrawFocusRect(const Rect& rect) {
   DrawFocusRect(RectF(rect));
 }
 
 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);
 }
 
 void Canvas::DrawImageInt(const ImageSkia& image, int x, int y) {
   cc::PaintFlags flags;
   DrawImageInt(image, x, y, flags);
 }
 
 void Canvas::DrawImageInt(const ImageSkia& image, int x, int y, uint8_t a) {
   cc::PaintFlags flags;
@@ skipping 218 matching lines @@
   flags.setFilterQuality(filter ? kLow_SkFilterQuality : kNone_SkFilterQuality);
   flags.setShader(CreateImageRepShaderForScale(
       image_rep, SkShader::kRepeat_TileMode, shader_scale,
       remove_image_scale ? image_rep.scale() : 1.f));
 
   // The rect will be filled by the bitmap.
   canvas_->drawRect(dest_rect, flags);
 }
 
 }  // namespace gfx