Support chrome.windows extension API events for browserless Panels.

chrome/browser/extensions/window_controller_list.h

 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_WINDOW_CONTROLLER_LIST_H_
 #define CHROME_BROWSER_EXTENSIONS_WINDOW_CONTROLLER_LIST_H_
 
 #include <list>
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
+#include "base/observer_list.h"
 #include "chrome/browser/extensions/window_controller.h"
 
 class Profile;
 class UIThreadExtensionFunction;
 
 namespace extensions {
 
+class WindowControllerListObserver;
+
 // Class to maintain a list of WindowControllers.
 class WindowControllerList {
  public:
   typedef std::list<WindowController*> ControllerList;
 
   WindowControllerList();
   ~WindowControllerList();
 
   void AddExtensionWindow(WindowController* window);
   void RemoveExtensionWindow(WindowController* window);
 
+  void AddObserver(WindowControllerListObserver* observer);
+  void RemoveObserver(WindowControllerListObserver* observer);
+
   // Returns a window matching the context the function was invoked in.
   WindowController* FindWindowForFunctionById(
       const UIThreadExtensionFunction* function,
       int id) const;
 
   // Returns the focused or last added window matching the context the function
   // was invoked in.
   WindowController* CurrentWindowForFunction(
       const UIThreadExtensionFunction* function) const;
 
   const ControllerList& windows() const { return windows_; }
 
   static WindowControllerList* GetInstance();
 
  private:
   friend struct DefaultSingletonTraits<WindowControllerList>;
 
   // Entries are not owned by this class and must be removed when destroyed.
   ControllerList windows_;
 
+  ObserverList<WindowControllerListObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowControllerList);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WINDOW_CONTROLLER_LIST_H_