Convert FWL_ERR into an enum class.

xfa/fwl/core/ifwl_app.h

 // Copyright 2014 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 XFA_FWL_CORE_IFWL_APP_H_
 #define XFA_FWL_CORE_IFWL_APP_H_
 
 // The FWL thread/app code contains three parallel classes, which reference each
@@ skipping 16 matching lines @@
 class IFWL_ThemeProvider;
 class IFWL_Widget;
 class IFWL_WidgetMgr;
 
 class IFWL_App {
  public:
   static IFWL_App* Create(IFWL_AdapterNative* pAdapter);
 
   virtual ~IFWL_App() {}
 
-  FWL_ERR Initialize();
-  FWL_ERR Finalize();
+  FWL_Error Initialize();
+  FWL_Error Finalize();
   IFWL_AdapterNative* GetAdapterNative();
   IFWL_WidgetMgr* GetWidgetMgr();
   IFWL_ThemeProvider* GetThemeProvider();
-  FWL_ERR SetThemeProvider(IFWL_ThemeProvider* pThemeProvider);
-  FWL_ERR Exit(int32_t iExitCode);
+  FWL_Error SetThemeProvider(IFWL_ThemeProvider* pThemeProvider);
+  FWL_Error Exit(int32_t iExitCode);
 
   // These call into polymorphic methods in the impl; no need to override.
   void Release();
 
   CFWL_AppImp* GetImpl() const { return m_pImpl.get(); }
 
   // Takes ownership of |pImpl|.
   void SetImpl(CFWL_AppImp* pImpl) { m_pImpl.reset(pImpl); }
 
   CFWL_NoteDriver* GetNoteDriver() const;
 
  private:
   IFWL_App() {}
 
   std::unique_ptr<CFWL_AppImp> m_pImpl;
 };
 
 IFWL_App* FWL_GetApp();
 void FWL_SetApp(IFWL_App* pApp);
 
 IFWL_AdapterNative* FWL_GetAdapterNative();
 IFWL_AdapterWidgetMgr* FWL_GetAdapterWidgetMgr();
 
 #endif  // XFA_FWL_CORE_IFWL_APP_H_