Lazily build the app list model.

chrome/browser/ui/app_list/extension_app_model_builder.cc

 // Copyright (c) 2012 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/app_list/extension_app_model_builder.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 32 matching lines @@
 }
 
 ExtensionAppModelBuilder::~ExtensionAppModelBuilder() {
   OnShutdown();
   OnShutdown(extension_registry_);
   if (!service_)
     model_->top_level_item_list()->RemoveObserver(this);
 }
 
 void ExtensionAppModelBuilder::InitializeWithService(
-    app_list::AppListSyncableService* service) {
+    app_list::AppListSyncableService* service,
+    app_list::AppListModel* model) {
   DCHECK(!service_ && !profile_);
-  model_ = service->model();
+  model_ = model;
   service_ = service;
   profile_ = service->profile();
   InitializePrefChangeRegistrars();
 
   BuildModel();
 }
 
 void ExtensionAppModelBuilder::InitializeWithProfile(
     Profile* profile,
     app_list::AppListModel* model) {
@@ skipping 259 matching lines @@
     app_list::AppListItem* item = item_list->item_at(idx + 1);
     if (item->GetItemType() == ExtensionAppItem::kItemType) {
       next = static_cast<ExtensionAppItem*>(item);
       break;
     }
   }
   // item->Move will call set_position, overriding the item's position.
   if (prev || next)
     static_cast<ExtensionAppItem*>(item)->Move(prev, next);
 }