Implement FPDF_VIEWERREF_GetName() API.

core/fpdfdoc/cpdf_viewerpreferences.h

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_FPDFDOC_CPDF_VIEWERPREFERENCES_H_
 #define CORE_FPDFDOC_CPDF_VIEWERPREFERENCES_H_
 
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
 
 class CPDF_Array;
 class CPDF_Dictionary;
 class CPDF_Document;
 
 class CPDF_ViewerPreferences {
  public:
   explicit CPDF_ViewerPreferences(CPDF_Document* pDoc);
   ~CPDF_ViewerPreferences();
 
   bool IsDirectionR2L() const;
   bool PrintScaling() const;
   int32_t NumCopies() const;
   CPDF_Array* PrintPageRange() const;
   CFX_ByteString Duplex() const;
 
+  // Gets the entry for |bsKey|. If the entry exists and it is of type name,
+  // then this method writes the value into |bsVal| and returns true. Otherwise
+  // returns false and |bsVal| is untouched. |bsVal| must not be NULL.
+  bool GenericName(const CFX_ByteString& bsKey, CFX_ByteString* bsVal) const;
+
  private:
   CPDF_Dictionary* GetViewerPreferences() const;
 
   CPDF_Document* const m_pDoc;
 };
 
 #endif  // CORE_FPDFDOC_CPDF_VIEWERPREFERENCES_H_