MacViews: Implement Force Touch/Mac dictionary lookup for Textfields.

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 1d26c17fcb5e4f1fdab0603871ebd7e22c79cc02..54503a78e7d98357010b51a95039cc0d617dd8c1 100644
--- a/ui/gfx/render_text_harfbuzz.h
+++ b/ui/gfx/render_text_harfbuzz.h
@@ -264,6 +264,10 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
   internal::TextRunList* GetRunList();
   const internal::TextRunList* GetRunList() const;
 
+  // RenderText:
+  bool GetDecoratedTextForRange(const Range& range,
+                                DecoratedText* decorated_text) const override;
+
   // Text run list for |layout_text_| and |display_text_|.
   // |display_run_list_| is created only when the text is elided.
   internal::TextRunList layout_run_list_;