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 13c8677c228ab447ac9b8ed6c5c3335a2e3b82c9..07bede1ca4e0b81b684fa412106c1e5e37a5e7c2 100644
--- a/ui/gfx/platform_font_mac.h
+++ b/ui/gfx/platform_font_mac.h
@@ -21,9 +21,9 @@ class PlatformFontMac : public PlatformFont {
   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
   virtual int GetHeight() const OVERRIDE;
   virtual int GetBaseline() 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;
@@ -48,7 +48,7 @@ class PlatformFontMac : public PlatformFont {
   // Cached metrics, generated at construction.
   int height_;
   int ascent_;
-  int average_width_;
+  float average_width_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformFontMac);
 };