Replace CJS_Runtime::Observer with CFX_Runtime<CJS_Runtime>::Observer

core/fxcrt/include/cfx_observable.h

Index: core/fxcrt/include/cfx_observable.h
diff --git a/core/fxcrt/include/cfx_observable.h b/core/fxcrt/include/cfx_observable.h
index b669e0d3d5b3b529dbd40c5ee9ddf2f01f5414f1..99a995128492f2f52f29db73196b7bcf8cb73fa0 100644
--- a/core/fxcrt/include/cfx_observable.h
+++ b/core/fxcrt/include/cfx_observable.h
@@ -45,10 +45,7 @@ class CFX_Observable {
 
   CFX_Observable() {}
   CFX_Observable(const CFX_Observable& that) = delete;
-  ~CFX_Observable() {
-    for (auto* pObserver : m_Observers)
-      pObserver->OnDestroy();
-  }
+  ~CFX_Observable() { NotifyObservers(); }
   void AddObserver(Observer* pObserver) {
     ASSERT(!pdfium::ContainsKey(m_Observers, pObserver));
     m_Observers.insert(pObserver);
@@ -57,6 +54,11 @@ class CFX_Observable {
     ASSERT(pdfium::ContainsKey(m_Observers, pObserver));
     m_Observers.erase(pObserver);
   }
+  void NotifyObservers() {
+    for (auto* pObserver : m_Observers)
+      pObserver->OnDestroy();
+    m_Observers.clear();
+  }
   CFX_Observable& operator=(const CFX_Observable& that) = delete;
 
  private: