Adding functions to the window_list_provider for accessing the activities window list

athena/wm/public/window_list_provider.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_PUBLIC_WINDOW_LIST_PROVIDER_H_
 #define ATHENA_WM_PUBLIC_WINDOW_LIST_PROVIDER_H_
 
 #include "athena/athena_export.h"
 #include "ui/aura/window.h"
 
 namespace athena {
 
+class WindowListProviderObserver;
+
 // Interface for an ordered list of aura::Window objects.
+// Note that lists returned by GetCurrentWindowList() will not change if any of
+// the other member functions will be called later.
 class ATHENA_EXPORT WindowListProvider {
  public:
   virtual ~WindowListProvider() {}
 
-  // Returns an ordered list of windows.
-  virtual aura::Window::Windows GetWindowList() const = 0;
+  // Adding/removing an observer to status changes.
+  virtual void AddObserver(WindowListProviderObserver* observer) = 0;
+  virtual void RemoveObserver(WindowListProviderObserver* observer) = 0;
+
+  // Returns an ordered list of the current window configuration.
+  virtual aura::Window::Windows GetCurrentWindowList() const = 0;
+
+  // Returns true if the |window| is part of the list.
+  virtual bool IsWindowInList(aura::Window* window) const = 0;
+
+  // Returns true if the given window is a window which can be handled by the
+  // WindowListProvider.
+  virtual bool IsValidWindow(aura::Window* window) const = 0;
+
+  // Moves a given |window| to the front of all windows of the window list.
+  // Note: The window has to be in the list already.
+  virtual void MoveToFront(aura::Window* window) = 0;
+
+  // Stacks a given |window| in direct front of a |reference_window|.
+  // Note: The |window| and |reference_window| has to be in the list already.
+  virtual void StackWindowFrontOf(aura::Window* window,
+                                  aura::Window* reference_window) = 0;
+
+  // Stacks a given |window| directly behind a |reference_window|.
+  // Note: The |window| and |reference_window| has to be in the list already.
+  virtual void StackWindowBehindTo(aura::Window* window,
+                                   aura::Window* reference_window) = 0;
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_WM_PUBLIC_WINDOW_LIST_PROVIDER_H_