Fix cursor positioning regression from r201136. GetCursorPos() shouldn't assume

ui/gfx/render_text_mac.h

Index: ui/gfx/render_text_mac.h
===================================================================
--- ui/gfx/render_text_mac.h	(revision 201137)
+++ ui/gfx/render_text_mac.h	(working copy)
@@ -39,9 +39,7 @@
   virtual SelectionModel AdjacentWordSelectionModel(
       const SelectionModel& selection,
       VisualCursorDirection direction) OVERRIDE;
-  virtual void GetGlyphBounds(size_t index,
-                              ui::Range* xspan,
-                              int* height) OVERRIDE;
+  virtual ui::Range GetGlyphBounds(size_t index) OVERRIDE;
   virtual std::vector<Rect> GetSubstringBounds(const ui::Range& range) OVERRIDE;
   virtual size_t TextIndexToLayoutIndex(size_t index) const OVERRIDE;
   virtual size_t LayoutIndexToTextIndex(size_t index) const OVERRIDE;