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

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
===================================================================
--- chrome/browser/sync/profile_sync_service.cc	(revision 29327)
+++ chrome/browser/sync/profile_sync_service.cc	(working copy)
@@ -151,11 +151,12 @@
   last_attempted_user_email_.clear();
 }
 
-void ProfileSyncService::EnableForUser() {
+void ProfileSyncService::EnableForUser(gfx::NativeWindow parent_window) {
   if (WizardIsVisible()) {
     // TODO(timsteele): Focus wizard.
     return;
   }
+  wizard_parent_window_ = parent_window;
   expecting_first_run_auth_needed_event_ = true;
 
   StartUp();
@@ -266,10 +267,12 @@
   FOR_EACH_OBSERVER(Observer, observers_, OnStateChanged());
 }
 
-void ProfileSyncService::ShowLoginDialog() {
+void ProfileSyncService::ShowLoginDialog(gfx::NativeWindow parent_window) {
   if (WizardIsVisible())
     return;
 
+  wizard_parent_window_ = parent_window;
+
   if (!auth_error_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("Sync.ReauthorizationTime",
                              base::TimeTicks::Now() - auth_error_time_);