refactor: remove WindowListObserver::OnWindowAdded() (#42979)

refactor: remove WindowListObserver::OnWindowRemove()

these have never been used

shell/browser/window_list.cc

@@ -51,9 +51,6 @@ void WindowList::AddWindow(NativeWindow* window) {
   // Push |window| on the appropriate list instance.
   WindowVector& windows = GetInstance()->windows_;
   windows.push_back(window);
-
-  for (WindowListObserver& observer : GetObservers())
-    observer.OnWindowAdded(window);
 }
 
 // static
@@ -61,9 +58,6 @@ void WindowList::RemoveWindow(NativeWindow* window) {
   WindowVector& windows = GetInstance()->windows_;
   std::erase(windows, window);
 
-  for (WindowListObserver& observer : GetObservers())
-    observer.OnWindowRemoved(window);
-
   if (windows.empty()) {
     for (WindowListObserver& observer : GetObservers())
       observer.OnWindowAllClosed();

shell/browser/window_list_observer.h

@@ -13,12 +13,6 @@ class NativeWindow;
 
 class WindowListObserver : public base::CheckedObserver {
  public:
-  // Called immediately after a window is added to the list.
-  virtual void OnWindowAdded(NativeWindow* window) {}
-
-  // Called immediately after a window is removed from the list.
-  virtual void OnWindowRemoved(NativeWindow* window) {}
-
   // Called when a window close is cancelled by beforeunload handler.
   virtual void OnWindowCloseCancelled(NativeWindow* window) {}