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 ebcfbf8ee4644dcfa8a97e35fc169bf303a08bd5..56b6821087b286e76acf9c52532d21973cc75073 100644
--- a/ash/launcher/launcher_view.h
+++ b/ash/launcher/launcher_view.h
@@ -10,6 +10,7 @@
 
 #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"
@@ -24,6 +25,7 @@ namespace ash {
 
 class LauncherDelegate;
 struct LauncherItem;
+class LauncherIconsObserver;
 class LauncherModel;
 class LauncherWindowCycler;
 class ViewModel;
@@ -64,6 +66,9 @@ class ASH_EXPORT LauncherView : public views::View,
   // isn't know.
   gfx::Rect GetIdealBoundsOfItemIcon(LauncherID id);
 
+  void AddIconsObserver(LauncherIconsObserver* observer);
+  void RemoveIconsObserver(LauncherIconsObserver* observer);
+
  private:
   class FadeOutAnimationDelegate;
   class StartFadeAnimationDelegate;
@@ -185,6 +190,8 @@ class ASH_EXPORT LauncherView : public views::View,
   // Used to handle cycling among windows.
   scoped_ptr<LauncherWindowCycler> cycler_;
 
+  ObserverList<LauncherIconsObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(LauncherView);
 };