Uses and returns the fractional width in text eliding

ui/gfx/platform_font_mac.h

Index: ui/gfx/platform_font_mac.h
diff --git a/ui/gfx/platform_font_mac.h b/ui/gfx/platform_font_mac.h
index e9d0714238c7510ba9695bd6d4944e3804ce91f3..401ea4c6e4aca790bcfded6a09d3fe269cf36903 100644
--- a/ui/gfx/platform_font_mac.h
+++ b/ui/gfx/platform_font_mac.h
@@ -22,9 +22,9 @@ class PlatformFontMac : public PlatformFont {
   virtual int GetHeight() const OVERRIDE;
   virtual int GetBaseline() const OVERRIDE;
   virtual int GetCapHeight() const OVERRIDE;
-  virtual int GetAverageCharacterWidth() const OVERRIDE;
-  virtual int GetStringWidth(const base::string16& text) const OVERRIDE;
-  virtual int GetExpectedTextWidth(int length) const OVERRIDE;
+  virtual float GetAverageCharacterWidth() const OVERRIDE;
+  virtual float GetStringWidth(const base::string16& text) const OVERRIDE;
+  virtual float GetExpectedTextWidth(int length) const OVERRIDE;
   virtual int GetStyle() const OVERRIDE;
   virtual std::string GetFontName() const OVERRIDE;
   virtual int GetFontSize() const OVERRIDE;
@@ -50,7 +50,7 @@ class PlatformFontMac : public PlatformFont {
   int height_;
   int ascent_;
   int cap_height_;
-  int average_width_;
+  float average_width_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformFontMac);
 };