Use enum class for subtypes of CPDF_Annot.

fpdfsdk/include/cpdfsdk_widgethandler.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 FPDFSDK_INCLUDE_CPDFSDK_WIDGETHANDLER_H_
 #define FPDFSDK_INCLUDE_CPDFSDK_WIDGETHANDLER_H_
 
 #include "core/fxcrt/include/fx_basic.h"
@@ skipping 10 matching lines @@
 
 #ifdef PDF_ENABLE_XFA
 class CXFA_FFWidget;
 #endif  // PDF_ENABLE_XFA
 
 class CPDFSDK_WidgetHandler : public IPDFSDK_AnnotHandler {
  public:
   explicit CPDFSDK_WidgetHandler(CPDFDoc_Environment* pApp);
   ~CPDFSDK_WidgetHandler() override;
 
-  CFX_ByteString GetType() override;
   FX_BOOL CanAnswer(CPDFSDK_Annot* pAnnot) override;
   CPDFSDK_Annot* NewAnnot(CPDF_Annot* pAnnot, CPDFSDK_PageView* pPage) override;
 #ifdef PDF_ENABLE_XFA
   CPDFSDK_Annot* NewAnnot(CXFA_FFWidget* hWidget,
                           CPDFSDK_PageView* pPage) override;
 #endif  // PDF_ENABLE_XFA
   void ReleaseAnnot(CPDFSDK_Annot* pAnnot) override;
   void DeleteAnnot(CPDFSDK_Annot* pAnnot) override;
   CFX_FloatRect GetViewBBox(CPDFSDK_PageView* pPageView,
                             CPDFSDK_Annot* pAnnot) override;
@@ skipping 70 matching lines @@
 
   void SetFormFiller(CFFL_IFormFiller* pFiller) { m_pFormFiller = pFiller; }
   CFFL_IFormFiller* GetFormFiller() { return m_pFormFiller; }
 
  private:
   CPDFDoc_Environment* m_pApp;
   CFFL_IFormFiller* m_pFormFiller;
 };
 
 #endif  // FPDFSDK_INCLUDE_CPDFSDK_WIDGETHANDLER_H_