Convert FWL_ERR into an enum class.

xfa/fwl/lightwidget/cfwl_theme.h

Index: xfa/fwl/lightwidget/cfwl_theme.h
diff --git a/xfa/fwl/lightwidget/cfwl_theme.h b/xfa/fwl/lightwidget/cfwl_theme.h
index 110a9dbb69cd3a62c371edd717a4af2d2d1ef0d5..ba20013c1090bf3d60f4f6eb925f8a99d661080d 100644
--- a/xfa/fwl/lightwidget/cfwl_theme.h
+++ b/xfa/fwl/lightwidget/cfwl_theme.h
@@ -31,26 +31,26 @@ class CFWL_Theme : public IFWL_ThemeProvider {
   uint32_t SetThemeID(IFWL_Widget* pWidget,
                       uint32_t dwThemeID,
                       FX_BOOL bChildren = TRUE) override;
-  FWL_ERR GetThemeMatrix(IFWL_Widget* pWidget, CFX_Matrix& matrix) override;
-  FWL_ERR SetThemeMatrix(IFWL_Widget* pWidget,
-                         const CFX_Matrix& matrix) override;
+  FWL_Error GetThemeMatrix(IFWL_Widget* pWidget, CFX_Matrix& matrix) override;
+  FWL_Error SetThemeMatrix(IFWL_Widget* pWidget,
+                           const CFX_Matrix& matrix) override;
   FX_BOOL DrawBackground(CFWL_ThemeBackground* pParams) override;
   FX_BOOL DrawText(CFWL_ThemeText* pParams) override;
   void* GetCapacity(CFWL_ThemePart* pThemePart,
                     CFWL_WidgetCapacity dwCapacity) override;
   FX_BOOL IsCustomizedLayout(IFWL_Widget* pWidget) override;
-  FWL_ERR GetPartRect(CFWL_ThemePart* pThemePart, CFX_RectF& rtPart) override;
+  FWL_Error GetPartRect(CFWL_ThemePart* pThemePart, CFX_RectF& rtPart) override;
   FX_BOOL IsInPart(CFWL_ThemePart* pThemePart,
                    FX_FLOAT fx,
                    FX_FLOAT fy) override;
   FX_BOOL CalcTextRect(CFWL_ThemeText* pParams, CFX_RectF& rect) override;
 
-  FWL_ERR Initialize();
-  FWL_ERR Finalize();
-  FWL_ERR SetFont(IFWL_Widget* pWidget,
-                  const FX_WCHAR* strFont,
-                  FX_FLOAT fFontSize,
-                  FX_ARGB rgbFont);
+  FWL_Error Initialize();
+  FWL_Error Finalize();
+  FWL_Error SetFont(IFWL_Widget* pWidget,
+                    const FX_WCHAR* strFont,
+                    FX_FLOAT fFontSize,
+                    FX_ARGB rgbFont);
   CFWL_WidgetTP* GetTheme(IFWL_Widget* pWidget);
 
  protected: