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

ui/gfx/render_text_mac.h

Index: ui/gfx/render_text_mac.h
diff --git a/ui/gfx/render_text_mac.h b/ui/gfx/render_text_mac.h
index 9b44a0627a6835e2d2b57535f21902bab6ff6fbf..f24b65e8676b074b4b2e42e4cdefebdd41ab692c 100644
--- a/ui/gfx/render_text_mac.h
+++ b/ui/gfx/render_text_mac.h
@@ -108,6 +108,10 @@ class GFX_EXPORT RenderTextMac : public RenderText {
   // Clears cached style. Doesn't update display text (e.g. eliding).
   void InvalidateStyle();
 
+  // RenderText:
+  bool GetDecoratedTextForRange(const Range& range,
+                                DecoratedText* decorated_text) override;
+
   // The Core Text line of text. Created by |EnsureLayout()|.
   base::ScopedCFTypeRef<CTLineRef> line_;