Handle app custom icon via aura::Window property.

chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h

Index: chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h
diff --git a/chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h b/chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h
index e1fd8767a114e4be4af3debd6ca8c8b24f7e9e4c..791a18a6fe89885bdf2d29cd1a4289511a17ff4f 100644
--- a/chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h
+++ b/chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h
@@ -60,11 +60,6 @@ class AppWindowLauncherItemController : public ash::ShelfItemDelegate,
   // Activates the window at position |index|.
   void ActivateIndexedApp(size_t index);
 
-  // Called when launcher item may need to be updated, eg. label or icon.
-  // TODO(khmel): Use aura::Window property and observe property change
-  // http://crbug.com/724292
-  virtual void UpdateLauncherItem() {}
-
   const WindowList& windows() const { return windows_; }
 
  protected:
@@ -87,6 +82,10 @@ class AppWindowLauncherItemController : public ash::ShelfItemDelegate,
  private:
   WindowList::iterator GetFromNativeWindow(aura::Window* window);
 
+  // Handles the case when the app window in this controller has been changed,
+  // and sets the new controller icon based on the currently active window.
+  void UpdateShelfItemIcon();
+
   // List of associated app windows
   WindowList windows_;