Re-land "Rename CFWL_Thread classes to ThreadImp"

xfa/include/fwl/core/fwl_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 _FWL_APP_H
 #define _FWL_APP_H
 class IFWL_NoteThread;
 class IFWL_AdapterNative;
 class IFWL_Widget;
 class IFWL_WidgetMgr;
 class IFWL_ThemeProvider;
 class IFWL_AdapterWidgetMgr;
-class IFWL_App;
+
 class IFWL_App : public IFWL_NoteThread {
  public:
   static IFWL_App* Create(IFWL_AdapterNative* pAdapter);
-  virtual FWL_ERR Initialize() = 0;
-  virtual FWL_ERR Finalize() = 0;
-  virtual IFWL_AdapterNative* GetAdapterNative() = 0;
-  virtual IFWL_WidgetMgr* GetWidgetMgr() = 0;
-  virtual FWL_ERR SetThemeProvider(IFWL_ThemeProvider* pThemeProvider) = 0;
-  virtual FWL_ERR Exit(int32_t iExitCode = 0) = 0;
+
+  FWL_ERR Initialize();
+  FWL_ERR Finalize();
+  IFWL_AdapterNative* GetAdapterNative();
+  IFWL_WidgetMgr* GetWidgetMgr();
+  IFWL_ThemeProvider* GetThemeProvider();
+  FWL_ERR SetThemeProvider(IFWL_ThemeProvider* pThemeProvider);
+  FWL_ERR Exit(int32_t iExitCode);
+
+ private:
+  IFWL_App() {}
 };
 IFWL_App* FWL_GetApp();
 void FWL_SetApp(IFWL_App* pApp);
 IFWL_AdapterNative* FWL_GetAdapterNative();
 IFWL_AdapterWidgetMgr* FWL_GetAdapterWidgetMgr();
 IFWL_ThemeProvider* FWL_GetThemeProvider();
 extern FWL_ERR FWL_Execute(const CFX_WideStringC& wsExecutable,
                            const CFX_WideStringC& wsParameters);
 FWL_ERR FWL_SetFullScreen(IFWL_Widget* pWidget, FX_BOOL bFullScreen);
 FX_BOOL FWL_AppIsActived();
 #endif