Fix ExtensionServiceTest.ClearExtensionData flakiness

chrome/browser/ui/app_list/app_list_syncable_service.cc

 // Copyright 2013 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/app_list_syncable_service.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/apps/drive/drive_app_provider.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 99 matching lines @@
       id == extension_misc::kWebStoreAppId)
     return true;
 #if defined(OS_CHROMEOS)
   if (id == file_manager::kFileManagerAppId || id == genius_app::kGeniusAppId)
     return true;
 #endif
   return false;
 }
 
 void UninstallExtension(ExtensionService* service, const std::string& id) {
-  if (service && service->GetInstalledExtension(id))
-    service->UninstallExtension(id, extensions::UNINSTALL_REASON_SYNC, NULL);
+  if (service && service->GetInstalledExtension(id)) {
+    service->UninstallExtension(id,
+                                extensions::UNINSTALL_REASON_SYNC,
+                                base::Bind(&base::DoNothing),
+                                NULL);
+  }
 }
 
 bool GetAppListItemType(AppListItem* item,
                         sync_pb::AppListSpecifics::AppListItemType* type) {
   const char* item_type = item->GetItemType();
   if (item_type == ExtensionAppItem::kItemType) {
     *type = sync_pb::AppListSpecifics::TYPE_APP;
   } else if (item_type == AppListFolderItem::kItemType) {
     *type = sync_pb::AppListSpecifics::TYPE_FOLDER;
   } else {
@@ skipping 775 matching lines @@
   } else {
     res += " { " + item_name + " }";
     res += " [" + item_ordinal.ToDebugString() + "]";
     if (!parent_id.empty())
       res += " <" + parent_id.substr(0, 8) + ">";
   }
   return res;
 }
 
 }  // namespace app_list