Makes the maximize/restore button handling

ash/launcher/launcher_delegate.h

Index: ash/launcher/launcher_delegate.h
diff --git a/ash/launcher/launcher_delegate.h b/ash/launcher/launcher_delegate.h
index cdc16344283b50e269e543adc352e228e347251b..674f557a690b7da2f808387aaf654ce6e3ef2a04 100644
--- a/ash/launcher/launcher_delegate.h
+++ b/ash/launcher/launcher_delegate.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include "ash/ash_export.h"
+#include "ash/launcher/launcher_types.h"
 #include "base/string16.h"
 
 namespace ui {
@@ -15,8 +16,6 @@ class MenuModel;
 
 namespace ash {
 
-struct LauncherItem;
-
 // Delegate for the Launcher.
 class ASH_EXPORT LauncherDelegate {
  public:
@@ -40,6 +39,10 @@ class ASH_EXPORT LauncherDelegate {
   // should be no context menu. The caller takes ownership of the returned
   // model.
   virtual ui::MenuModel* CreateContextMenu(const LauncherItem& item) = 0;
+
+  // Returns the id of the item associated with the specified window, or 0 if
+  // there isn't one.
+  virtual ash::LauncherID GetIDByWindow(aura::Window* window) = 0;
 };
 
 }  // namespace ash