Make code compile with clang_use_chrome_plugin (part VI)

xfa/fwl/basewidget/ifwl_tooltip.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_BASEWIDGET_IFWL_TOOLTIP_H_
 #define XFA_FWL_BASEWIDGET_IFWL_TOOLTIP_H_
 
 #include "xfa/fwl/core/ifwl_form.h"
 
 class CFWL_WidgetImpProperties;
 class IFWL_ToolTip;
 
 #define FWL_CLASS_ToolTip L"FWL_TOOLTIP"
 #define FWL_STYLEEXT_TTP_Rectangle (0L << 3)
 #define FWL_STYLEEXT_TTP_RoundCorner (1L << 3)
 #define FWL_STYLEEXT_TTP_Balloon (1L << 4)
 #define FWL_STYLEEXT_TTP_Multiline (1L << 5)
 #define FWL_STYLEEXT_TTP_NoAnchor (1L << 6)
 
 class IFWL_ToolTipDP : public IFWL_DataProvider {
  public:
-  virtual FWL_Error GetCaption(IFWL_Widget* pWidget,
-                               CFX_WideString& wsCaption) = 0;
+  // IFWL_DataProvider
+  FWL_Error GetCaption(IFWL_Widget* pWidget,
+                       CFX_WideString& wsCaption) override = 0;
+
   virtual int32_t GetInitialDelay(IFWL_Widget* pWidget) = 0;
   virtual int32_t GetAutoPopDelay(IFWL_Widget* pWidget) = 0;
   virtual CFX_DIBitmap* GetToolTipIcon(IFWL_Widget* pWidget) = 0;
   virtual CFX_SizeF GetToolTipIconSize(IFWL_Widget* pWidget) = 0;
 };
 
 class IFWL_ToolTip : public IFWL_Form {
  public:
   static IFWL_ToolTip* Create(const CFWL_WidgetImpProperties& properties,
                               IFWL_Widget* pOuter);
 
   void SetAnchor(const CFX_RectF& rtAnchor);
   void Show();
   void Hide();
 
  protected:
   IFWL_ToolTip();
 };
 
 #endif  // XFA_FWL_BASEWIDGET_IFWL_TOOLTIP_H_