Adding functions to the window_list_provider for accessing the activities window list

athena/wm/window_list_provider_impl.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ATHENA_WM_WINDOW_LIST_PROVIDER_IMPL_H_
 #define ATHENA_WM_WINDOW_LIST_PROVIDER_IMPL_H_
 
 #include "athena/wm/public/window_list_provider.h"
+#include "ui/aura/window_observer.h"
 
 namespace athena {
 
+class WindowListProviderObserver;
+
 // This implementation of the WindowListProviderImpl uses the same order as in
 // the container window's stacking order.
-class ATHENA_EXPORT WindowListProviderImpl : public WindowListProvider {
+class ATHENA_EXPORT WindowListProviderImpl : public WindowListProvider,
+                                             public aura::WindowObserver {
  public:
   explicit WindowListProviderImpl(aura::Window* container);
   virtual ~WindowListProviderImpl();
 
  private:
   // WindowListProvider:
+  virtual void AddObserver(WindowListProviderObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(WindowListProviderObserver* observer) OVERRIDE;
   virtual aura::Window::Windows GetWindowList() const OVERRIDE;
+  virtual bool IsWindowInList(aura::Window* window) const OVERRIDE;
+  virtual bool IsValidWindow(aura::Window* window) const OVERRIDE;
+  virtual void MoveToFront(aura::Window* window) OVERRIDE;
+  virtual void StackWindowFrontOf(aura::Window* window,
+                                  aura::Window*reference_window) OVERRIDE;
+  virtual void StackWindowBehindTo(aura::Window* window,
+                                   aura::Window*reference_window) OVERRIDE;
+
+  // aura::WindowObserver:
+  virtual void OnWindowAdded(aura::Window* new_window) OVERRIDE;
+  virtual void OnWillRemoveWindow(aura::Window* old_window) OVERRIDE;
+  virtual void OnWindowStackingChanged(aura::Window* window) OVERRIDE;
 
   aura::Window* container_;
+  ObserverList<WindowListProviderObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowListProviderImpl);
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_WM_WINDOW_LIST_PROVIDER_IMPL_H_