Add observer for BAAnnots from Javascript

fpdfsdk/include/cpdfsdk_widget.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_WIDGET_H_
 #define FPDFSDK_INCLUDE_CPDFSDK_WIDGET_H_
 
 #include <set>
@@ skipping 17 matching lines @@
 class CPDFSDK_InterForm;
 class CPDFSDK_PageView;
 
 #ifdef PDF_ENABLE_XFA
 class CXFA_FFWidget;
 class CXFA_FFWidgetHandler;
 #endif  // PDF_ENABLE_XFA
 
 class CPDFSDK_Widget : public CPDFSDK_BAAnnot {
  public:
-  class Observer {
+  class Observer : public CPDFSDK_Annot::Observer {
    public:
     explicit Observer(CPDFSDK_Widget** pWatchedPtr);
-    ~Observer();
+    ~Observer() override;
 
-    void OnWidgetDestroyed();
+    void OnAnnotDestroyed() override;
 
    private:
     CPDFSDK_Widget** m_pWatchedPtr;
   };
 
 #ifdef PDF_ENABLE_XFA
   CXFA_FFWidget* GetMixXFAWidget() const;
   CXFA_FFWidget* GetGroupMixXFAWidget();
   CXFA_FFWidgetHandler* GetXFAWidgetHandler() const;
 
@@ skipping 14 matching lines @@
                                   CXFA_FFWidget* hWidget,
                                   CPDF_FormField* pFormField,
                                   CPDF_FormControl* pFormControl);
 #endif  // PDF_ENABLE_XFA
 
   CPDFSDK_Widget(CPDF_Annot* pAnnot,
                  CPDFSDK_PageView* pPageView,
                  CPDFSDK_InterForm* pInterForm);
   ~CPDFSDK_Widget() override;
 
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
-
   bool IsSignatureWidget() const override;
   CPDF_Action GetAAction(CPDF_AAction::AActionType eAAT) override;
   FX_BOOL IsAppearanceValid() override;
 
   int GetLayoutOrder() const override;
 
   int GetFieldType() const;
   int GetFieldFlags() const;
   int GetRotate() const;
 
@@ skipping 82 matching lines @@
   CPWL_Color GetBorderPWLColor() const;
   CPWL_Color GetFillPWLColor() const;
 
   void AddImageToAppearance(const CFX_ByteString& sAPType, CPDF_Stream* pImage);
   void RemoveAppearance(const CFX_ByteString& sAPType);
 
   CPDFSDK_InterForm* const m_pInterForm;
   FX_BOOL m_bAppModified;
   int32_t m_nAppAge;
   int32_t m_nValueAge;
-  std::set<Observer*> m_Observers;
 
 #ifdef PDF_ENABLE_XFA
   mutable CXFA_FFWidget* m_hMixXFAWidget;
   mutable CXFA_FFWidgetHandler* m_pWidgetHandler;
 #endif  // PDF_ENABLE_XFA
 };
 
 #endif  // FPDFSDK_INCLUDE_CPDFSDK_WIDGET_H_