Ensure the ExtensionSystem is ready before initializing an ExtensionAppModelBuilder

chrome/browser/ui/app_list/app_list_syncable_service.h

Index: chrome/browser/ui/app_list/app_list_syncable_service.h
diff --git a/chrome/browser/ui/app_list/app_list_syncable_service.h b/chrome/browser/ui/app_list/app_list_syncable_service.h
index 0bd7e266ec59dd0cb88ee335d6f0635cc434da38..52ec42349167473b322f9fbce5e925aa20224d38 100644
--- a/chrome/browser/ui/app_list/app_list_syncable_service.h
+++ b/chrome/browser/ui/app_list/app_list_syncable_service.h
@@ -7,25 +7,41 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
 class ExtensionAppModelBuilder;
+class ExtensionService;
 class Profile;
 
 namespace app_list {
 
 class AppListModel;
 
-// Keyed Service that owns, stores, and syncs an AppListModel for a profile.
+// Keyed Service that owns, stores, and syncs an AppListModel for an
+// ExtensionSystem and corresponding profile.
 // TODO(stevenjb): Integrate with Sync. crbug.com/305024.
-class AppListSyncableService : public BrowserContextKeyedService {
+class AppListSyncableService : public BrowserContextKeyedService,
+                               public content::NotificationObserver {
  public:
-  explicit AppListSyncableService(Profile* profile);
+  // Create an empty model. Then, if |extension_service| is non-NULL and ready,
+  // populate it. Otherwise populate the model once extensions become ready.
+  AppListSyncableService(Profile* profile, ExtensionService* extension_service);
+
   virtual ~AppListSyncableService();
 
   AppListModel* model() { return model_.get(); }
 
  private:
+  void BuildModel();
+
+  // content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
   Profile* profile_;
+  content::NotificationRegistrar registrar_;
   scoped_ptr<AppListModel> model_;
   scoped_ptr<ExtensionAppModelBuilder> apps_builder_;