Add float version of gfx::Range

ui/gfx/render_text_harfbuzz.h

Index: ui/gfx/render_text_harfbuzz.h
diff --git a/ui/gfx/render_text_harfbuzz.h b/ui/gfx/render_text_harfbuzz.h
index d0e167ecbed1cc421ec7b9eef17fb1aa0d8e50f1..aad09f0e017d235dbf67498f01fb15d7508e6ac1 100644
--- a/ui/gfx/render_text_harfbuzz.h
+++ b/ui/gfx/render_text_harfbuzz.h
@@ -20,13 +20,13 @@ class BreakIterator;
 
 namespace gfx {
 
-namespace internal {
+class Range;
+class RangeF;
 
-// TODO(ckocagil): Make Range a template class and RangeF an instance of it.
-typedef std::pair<float, float> RangeF;
+namespace internal {
 
 // Applies std::round to the start and end values of the given RangeF.
-Range GFX_EXPORT RoundRangeF(const RangeF& range_f);
+GFX_EXPORT Range RoundRangeF(const RangeF& range_f);
 
 struct GFX_EXPORT TextRunHarfBuzz {
   TextRunHarfBuzz();