Fix ExtensionServiceTest.ClearExtensionData flakiness

chrome/browser/ui/webui/extensions/extension_settings_handler.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/webui/extensions/extension_settings_handler.h"
 
 #include "apps/app_load_service.h"
 #include "apps/app_window.h"
 #include "apps/app_window_registry.h"
 #include "apps/saved_files_service.h"
@@ skipping 742 matching lines @@
         ExtensionRegistry::Get(Profile::FromWebUI(web_ui()))->GetExtensionById(
             extension_id_prompting_, ExtensionRegistry::TERMINATED);
     was_terminated = true;
   }
   if (!extension)
     return;
 
   extension_service_->UninstallExtension(
       extension_id_prompting_,
       extensions::UNINSTALL_REASON_USER_INITIATED,
+      base::Bind(&base::DoNothing),
       NULL);  // Error.
   extension_id_prompting_ = "";
 
   // There will be no EXTENSION_UNLOADED notification for terminated
   // extensions as they were already unloaded.
   if (was_terminated)
     HandleRequestExtensionsData(NULL);
 }
 
 void ExtensionSettingsHandler::ExtensionUninstallCanceled() {
@@ skipping 619 matching lines @@
     extension_service_->EnableExtension(extension_id);
   } else {
     ExtensionErrorReporter::GetInstance()->ReportError(
         base::UTF8ToUTF16(JoinString(requirement_errors, ' ')),
         true);  // Be noisy.
   }
   requirements_checker_.reset();
 }
 
 }  // namespace extensions