fix: On close trying to remove observer from an empty collection leads to an access violation (electron#15739) (electron#18992)

codebytere · MarshallOfSound · commit b18a012bfdde · 2019-06-26T11:04:30.000-07:00
diff --git a/atom/browser/api/atom_api_web_contents.h b/atom/browser/api/atom_api_web_contents.h
@@ -293,7 +293,9 @@ class WebContents : public mate::TrackableObject<WebContents>,
     observers_.AddObserver(obs);
   }
   void RemoveObserver(ExtendedWebContentsObserver* obs) {
-    observers_.RemoveObserver(obs);
+    // Trying to remove from an empty collection leads to an access violation
+    if (observers_.might_have_observers())
+      observers_.RemoveObserver(obs);
   }
 
   bool EmitNavigationEvent(const std::string& event,

Original file line number	Diff line number	Diff line change
`@@ -293,7 +293,9 @@ class WebContents : public mate::TrackableObject<WebContents>,`
`293`	`293`	`observers_.AddObserver(obs);`
`294`	`294`	`}`
`295`	`295`	`void RemoveObserver(ExtendedWebContentsObserver* obs) {`
`296`		`- observers_.RemoveObserver(obs);`
	`296`	`+ // Trying to remove from an empty collection leads to an access violation`
	`297`	`+ if (observers_.might_have_observers())`
	`298`	`+ observers_.RemoveObserver(obs);`
`297`	`299`	`}`
`298`	`300`
`299`	`301`	`bool EmitNavigationEvent(const std::string& event,`