MacViews: Use RenderTextHarfBuzz only for Textfields

ui/gfx/render_text_pango.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_RENDER_TEXT_PANGO_H_
 #define UI_GFX_RENDER_TEXT_PANGO_H_
 
 #include <pango/pango.h>
 #include <vector>
 
 #include "ui/gfx/render_text.h"
 
 namespace gfx {
 
 // RenderTextPango is the Linux implementation of RenderText using Pango.
 class RenderTextPango : public RenderText {
  public:
   RenderTextPango();
   ~RenderTextPango() override;
 
   // Overridden from RenderText:
+  scoped_ptr<RenderText> CreateInstanceOfSameType() const override;
   Size GetStringSize() override;
   SelectionModel FindCursorPosition(const Point& point) override;
   std::vector<FontSpan> GetFontSpansForTesting() override;
 
  protected:
   // Overridden from RenderText:
   int GetLayoutTextBaseline() override;
   SelectionModel AdjacentCharSelectionModel(
       const SelectionModel& selection,
       VisualCursorDirection direction) override;
@@ skipping 47 matching lines @@
 
   // The text in the |layout_|.
   const char* layout_text_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderTextPango);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_PANGO_H_