[Sync] Make BackendMigrator not wait for full sync cycles

chrome/browser/sync/internal_api/sync_manager.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_INTERNAL_API_SYNC_MANAGER_H_
 #define CHROME_BROWSER_SYNC_INTERNAL_API_SYNC_MANAGER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 439 matching lines @@
   // *not* override an explicit passphrase set previously.
   void SetPassphrase(const std::string& passphrase, bool is_explicit);
 
   // Set the datatypes we want to encrypt and encrypt any nodes as necessary.
   // Note: |encrypted_types| will be unioned with the current set of encrypted
   // types, as we do not currently support decrypting datatypes.
   void EncryptDataTypes(const syncable::ModelTypeSet& encrypted_types);
 
   // Puts the SyncScheduler into a mode where no normal nudge or poll traffic
   // will occur, but calls to RequestConfig will be supported.  If |callback|
-  // is provided, it will be invoked (from the internal SyncScheduler) when
+  // is non-null, it will be invoked (from the internal SyncScheduler) when
   // the thread has changed to configuration mode.
-  void StartConfigurationMode(ModeChangeCallback* callback);
+  void StartConfigurationMode(const base::Closure& callback);
 
   // Switches the mode of operation to CONFIGURATION_MODE and
   // schedules a config task to fetch updates for |types|.
   void RequestConfig(const syncable::ModelTypeBitSet& types,
      sync_api::ConfigureReason reason);
 
-  void RequestCleanupDisabledTypes();
+  void RequestCleanupDisabledTypes(const base::Closure& callback);
 
   // Request a clearing of all data on the server
   void RequestClearServerData();
 
   // Adds a listener to be notified of sync events.
   // NOTE: It is OK (in fact, it's probably a good idea) to call this before
   // having received OnInitializationCompleted.
   void AddObserver(Observer* observer);
 
   // Remove the given observer.  Make sure to call this if the
@@ skipping 64 matching lines @@
 };
 
 bool InitialSyncEndedForTypes(syncable::ModelTypeSet types, UserShare* share);
 
 // Returns the string representation of a PassphraseRequiredReason value.
 std::string PassphraseRequiredReasonToString(PassphraseRequiredReason reason);
 
 } // namespace sync_api
 
 #endif  // CHROME_BROWSER_SYNC_INTERNAL_API_SYNC_MANAGER_H_