[cros] Fake a stub user login when no --login-manager and --login-user are given.

chrome/browser/extensions/extension_startup_browsertest.cc

Index: chrome/browser/extensions/extension_startup_browsertest.cc
diff --git a/chrome/browser/extensions/extension_startup_browsertest.cc b/chrome/browser/extensions/extension_startup_browsertest.cc
index 5c14c654109e49ac55b82b24b1167fe610035e54..7cfd2e057ccfa1cbb9092517c28435f6ca566692 100644
--- a/chrome/browser/extensions/extension_startup_browsertest.cc
+++ b/chrome/browser/extensions/extension_startup_browsertest.cc
@@ -18,6 +18,7 @@
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/testing_profile.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
@@ -53,7 +54,7 @@ class ExtensionStartupTestBase : public InProcessBrowserTest {
   virtual bool SetUpUserDataDirectory() {
     FilePath profile_dir;
     PathService::Get(chrome::DIR_USER_DATA, &profile_dir);
-    profile_dir = profile_dir.AppendASCII("Default");
+    profile_dir = profile_dir.AppendASCII(TestingProfile::kTestUserProfileDir);
     file_util::CreateDirectory(profile_dir);
 
     preferences_file_ = profile_dir.AppendASCII("Preferences");