Handle app custom icon via aura::Window property.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_ASH_LAUNCHER_EXTENSION_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_EXTENSION_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h"
 
+class ChromeLauncherController;
+
 namespace extensions {
 class AppWindow;
 }
 
 // Shelf item delegate for extension app windows.
 class ExtensionAppWindowLauncherItemController
     : public AppWindowLauncherItemController {
  public:
-  explicit ExtensionAppWindowLauncherItemController(
-      const ash::ShelfID& shelf_id);
+  ExtensionAppWindowLauncherItemController(const ash::ShelfID& shelf_id,
+                                           ChromeLauncherController* owner);
 
   ~ExtensionAppWindowLauncherItemController() override;
 
   void AddAppWindow(extensions::AppWindow* app_window);
 
   // AppWindowLauncherItemController:
   ash::MenuItemList GetAppMenuItems(int event_flags) override;
   void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ExtensionAppWindowLauncherItemController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_EXTENSION_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_