athena: Add a minimized state for the home-card.

athena/wm/public/window_manager.h

Index: athena/wm/public/window_manager.h
diff --git a/athena/wm/public/window_manager.h b/athena/wm/public/window_manager.h
index 9cbd79e21ff5a06c98c1135f50dc3d7b6466356e..23aab7f4a4967eecc30e6b8552e33113489f0179 100644
--- a/athena/wm/public/window_manager.h
+++ b/athena/wm/public/window_manager.h
@@ -9,6 +9,8 @@
 
 namespace athena {
 
+class WindowManagerObserver;
+
 // Manages the application, web windows.
 class ATHENA_EXPORT WindowManager {
  public:
@@ -16,10 +18,14 @@ class ATHENA_EXPORT WindowManager {
   // implementation.
   static WindowManager* Create();
   static void Shutdown();
+  static WindowManager* GetInstance();
 
   virtual ~WindowManager() {}
 
   virtual void ToggleOverview() = 0;
+
+  virtual void AddObserver(WindowManagerObserver* observer) = 0;
+  virtual void RemoveObserver(WindowManagerObserver* observer) = 0;
 };
 
 }  // namespace athena