The login dialog was being opened with the main browser window as a parent in...

chrome/browser/sync/profile_sync_service_unittest.cc

 // Copyright (c) 2006-2008 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.
 
 #ifdef CHROME_PERSONALIZATION
 
 #include <stack>
 #include <vector>
 
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 269 matching lines @@
   }
 
   void StartSyncService() {
     if (!service_.get()) {
       service_.reset(new TestProfileSyncService(profile_.get()));
       service_->Initialize();
     }
     // The service may have already started sync automatically if it's already
     // enabled by user once.
     if (!service_->HasSyncSetupCompleted())
-      service_->EnableForUser();
+      service_->EnableForUser(NULL);
   }
   void StopSyncService(SaveOption save) {
     if (save == DONT_SAVE_TO_STORAGE)
       service_->DisableForUser();
     service_.reset();
   }
 
   // Load (or re-load) the bookmark model.  |load| controls use of the
   // bookmarks file on disk.  |save| controls whether the newly loaded
   // bookmark model will write out a bookmark file as it goes.
@@ skipping 966 matching lines @@
   StartSyncService();
 
   // Make sure we're back in sync.  In real life, the user would need
   // to reauthenticate before this happens, but in the test, authentication
   // is sidestepped.
   ExpectBookmarkModelMatchesTestData();
   ExpectModelMatch();
 }
 
 #endif  // CHROME_PERSONALIZATION