Layout panels on top of their launcher icons

ash/launcher/launcher_view.h

Index: ash/launcher/launcher_view.h
diff --git a/ash/launcher/launcher_view.h b/ash/launcher/launcher_view.h
index 59cff170b22f831ebbfffdaf71dbbbce9da1a772..fe73b34d393309be29f8cfc2b7457a65641b9797 100644
--- a/ash/launcher/launcher_view.h
+++ b/ash/launcher/launcher_view.h
@@ -11,6 +11,7 @@
 
 #include "ash/launcher/launcher_button_host.h"
 #include "ash/launcher/launcher_model_observer.h"
+#include "base/observer_list.h"
 #include "ui/views/context_menu_controller.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
@@ -25,6 +26,7 @@ namespace ash {
 
 class LauncherDelegate;
 struct LauncherItem;
+class LauncherIconsObserver;
 class LauncherModel;
 class ViewModel;
 
@@ -64,6 +66,10 @@ class ASH_EXPORT LauncherView : public views::View,
   // isn't know.
   gfx::Rect GetIdealBoundsOfItemIcon(LauncherID id);
 
+
+  void AddIconsObserver(LauncherIconsObserver* observer);
+  void RemoveIconsObserver(LauncherIconsObserver* observer);
+
   // Returns true if we're showing a menu.
   bool IsShowingMenu() const;
 
@@ -188,6 +194,8 @@ class ASH_EXPORT LauncherView : public views::View,
   scoped_ptr<views::MenuRunner> launcher_menu_runner_;
 #endif
 
+  ObserverList<LauncherIconsObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(LauncherView);
 };