MacViews: Use RenderTextHarfBuzz only for Textfields

ui/gfx/render_text_pango.cc

Index: ui/gfx/render_text_pango.cc
diff --git a/ui/gfx/render_text_pango.cc b/ui/gfx/render_text_pango.cc
index 27f00461093003ac75910ee677ca6271d60b70a1..8be0e6f7358677a391d5719104ebea828ebe9ee6 100644
--- a/ui/gfx/render_text_pango.cc
+++ b/ui/gfx/render_text_pango.cc
@@ -89,6 +89,10 @@ RenderTextPango::~RenderTextPango() {
   ResetLayout();
 }
 
+scoped_ptr<RenderText> RenderTextPango::NewInstance() const {
+  return scoped_ptr<RenderTextPango>(new RenderTextPango);
+}
+
 Size RenderTextPango::GetStringSize() {
   EnsureLayout();
   int width = 0, height = 0;