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 dc1d8d1b01985d6a5cb5a5d0253db079c2b03d07..f367c3a33aab14cdd2bd4cdedd7df1474429abee 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/focus/focus_manager.h"
@@ -27,6 +28,7 @@ namespace ash {
 
 class LauncherDelegate;
 struct LauncherItem;
+class LauncherIconObserver;
 class LauncherModel;
 
 namespace internal {
@@ -66,6 +68,9 @@ class ASH_EXPORT LauncherView : public views::View,
   // isn't know.
   gfx::Rect GetIdealBoundsOfItemIcon(LauncherID id);
 
+  void AddIconObserver(LauncherIconObserver* observer);
+  void RemoveIconObserver(LauncherIconObserver* observer);
+
   // Returns true if we're showing a menu.
   bool IsShowingMenu() const;
 
@@ -169,6 +174,10 @@ class ASH_EXPORT LauncherView : public views::View,
   // item in |model_|.
   scoped_ptr<views::ViewModel> view_model_;
 
+  // Last index of a launcher button that is visible
+  // (does not go into overflow).
+  int last_visible_index_;
+
   scoped_ptr<views::BoundsAnimator> bounds_animator_;
 
   views::ImageButton* overflow_button_;
@@ -198,6 +207,8 @@ class ASH_EXPORT LauncherView : public views::View,
   scoped_ptr<views::MenuRunner> launcher_menu_runner_;
 #endif
 
+  ObserverList<LauncherIconObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(LauncherView);
 };