make new syncer thread the default.

chrome/browser/sync/profile_sync_service.cc

 // Copyright (c) 2011 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/sync/profile_sync_service.h"
 
 #include <map>
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 580 matching lines @@
   // we want UI to update itself and no longer allow the user to press "clear"
   if (clear_server_data_state_ != CLEAR_SUCCEEDED) {
     clear_server_data_state_ = CLEAR_SUCCEEDED;
     NotifyObservers();
   }
 }
 
 void ProfileSyncService::OnPassphraseRequired(bool for_decryption) {
   DCHECK(backend_.get());
   DCHECK(backend_->IsNigoriEnabled());
+
+  // TODO(lipalani) : add this check to other locations as well.
+  if (unrecoverable_error_detected_) {
+    // When unrecoverable error is detected we post a task to shutdown the
+    // backend. The task might not have executed yet.
+    return;
+  }
   observed_passphrase_required_ = true;
   passphrase_required_for_decryption_ = for_decryption;
 
   if (!cached_passphrase_.value.empty()) {
     SetPassphrase(cached_passphrase_.value,
                   cached_passphrase_.is_explicit,
                   cached_passphrase_.is_creation);
     cached_passphrase_ = CachedPassphrase();
     return;
   }
@@ skipping 649 matching lines @@
   // is initialized, all enabled data types are consistent with one
   // another, and no unrecoverable error has transpired.
   if (unrecoverable_error_detected_)
     return false;
 
   if (!data_type_manager_.get())
     return false;
 
   return data_type_manager_->state() == DataTypeManager::CONFIGURED;
 }