Scale focus outline thickness with zoom level.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 2166 matching lines @@
   }
 }
 
 void ComputedStyle::setOffsetPath(PassRefPtr<StylePath> path) {
   m_rareNonInheritedData.access()->m_transform.access()->m_motion.m_path = path;
 }
 
 int ComputedStyle::outlineOutsetExtent() const {
   if (!hasOutline())
     return 0;
-  if (outlineStyleIsAuto())
-    return GraphicsContext::focusRingOutsetExtent(outlineOffset(),
-                                                  outlineWidth());
+  if (outlineStyleIsAuto()) {
+    return GraphicsContext::focusRingOutsetExtent(
+        outlineOffset(), getOutlineStrokeWidthForFocusRing());
+  }
   return std::max(0, saturatedAddition(outlineWidth(), outlineOffset()));
 }
 
+float ComputedStyle::getOutlineStrokeWidthForFocusRing() const {
+#if OS(MACOSX)
+  return outlineWidth();
+#else
+  // Draw an outline with thickness in proportion to the zoom level, but never
+  // less than 1 pixel so that it remains visible.
+  return std::max(effectiveZoom(), 1.f);
+#endif
+}
+
 bool ComputedStyle::columnRuleEquivalent(
     const ComputedStyle* otherStyle) const {
   return columnRuleStyle() == otherStyle->columnRuleStyle() &&
          columnRuleWidth() == otherStyle->columnRuleWidth() &&
          visitedDependentColor(CSSPropertyColumnRuleColor) ==
              otherStyle->visitedDependentColor(CSSPropertyColumnRuleColor);
 }
 
 TextEmphasisMark ComputedStyle::getTextEmphasisMark() const {
   TextEmphasisMark mark =
@@ skipping 147 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink