Use Ash's ShelfWindowWatcher for app panel windows.

chrome/browser/ui/ash/launcher/extension_app_window_launcher_controller.cc

 // 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.
 
 #include "chrome/browser/ui/ash/launcher/extension_app_window_launcher_controller.h"
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shelf/shelf_delegate.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window_property.h"
@@ skipping 109 matching lines @@
     aura::Window* window) {
   UnregisterApp(window);
 }
 
 void ExtensionAppWindowLauncherController::RegisterApp(AppWindow* app_window) {
   // Windows created by IME extension should be treated the same way as the
   // virtual keyboard window, which does not register itself in launcher.
   if (app_window->is_ime_window())
     return;
 
+  // Ash's ShelfWindowWatcher handles app panel windows separately.
+  if (app_window->window_type_is_panel()) {
+    // Load panel app icons now. ShelfWindowWatcher cannot easily trigger this,
+    // and ShelfModel::Set cannot be called in ShelfItemAdded, since ShelfView
+    // may not have added a view for the new shelf item at that point.
+    const std::string& app_id = app_window->extension_id();
+    AppIconLoader* app_icon_loader = owner()->GetAppIconLoaderForApp(app_id);
+    if (app_icon_loader) {
+      app_icon_loader->FetchImage(app_id);
+      app_icon_loader->UpdateImage(app_id);
+    }
+    return;
+  }
+
   aura::Window* window = app_window->GetNativeWindow();
   // Get the app's shelf identifier and add an entry to the map.
   DCHECK(window_to_app_shelf_id_map_.find(window) ==
          window_to_app_shelf_id_map_.end());
   const std::string app_shelf_id = GetAppShelfId(app_window);
   window_to_app_shelf_id_map_[window] = app_shelf_id;
   window->AddObserver(this);
 
   // Find or create an item controller and launcher item.
   std::string app_id = app_window->extension_id();
   ash::ShelfItemStatus status = ash::wm::IsActiveWindow(window)
                                     ? ash::STATUS_ACTIVE
                                     : ash::STATUS_RUNNING;
   AppControllerMap::iterator app_controller_iter =
       app_controller_map_.find(app_shelf_id);
   ash::ShelfID shelf_id = 0;
 
   if (app_controller_iter != app_controller_map_.end()) {
     ExtensionAppWindowLauncherItemController* controller =
         app_controller_iter->second;
     DCHECK(controller->app_id() == app_id);
     shelf_id = controller->shelf_id();
     controller->AddAppWindow(app_window);
   } else {
-    LauncherItemController::Type type =
-        app_window->window_type_is_panel()
-            ? LauncherItemController::TYPE_APP_PANEL
-            : LauncherItemController::TYPE_APP;
+    LauncherItemController::Type type = LauncherItemController::TYPE_APP;
     std::string launch_id = GetLaunchId(app_window);
     ExtensionAppWindowLauncherItemController* controller =
         new ExtensionAppWindowLauncherItemController(type, app_id, launch_id,
                                                      owner());
     controller->AddAppWindow(app_window);
     // If there is already a shelf id mapped to this app_shelf_id (e.g. pinned),
     // use that shelf item.
     shelf_id =
         ash::WmShell::Get()->shelf_delegate()->GetShelfIDForAppIDAndLaunchID(
             app_id, launch_id);
@@ skipping 56 matching lines @@
   WindowToAppShelfIdMap::iterator window_iter =
       window_to_app_shelf_id_map_.find(window);
   if (window_iter == window_to_app_shelf_id_map_.end())
     return nullptr;
   AppControllerMap::iterator app_controller_iter =
       app_controller_map_.find(window_iter->second);
   if (app_controller_iter == app_controller_map_.end())
     return nullptr;
   return app_controller_iter->second;
 }