[Sync] Make BackendMigrator not wait for full sync cycles

chrome/browser/sync/glue/sync_backend_registrar.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_GLUE_SYNC_BACKEND_REGISTRAR_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_REGISTRAR_H_
 #pragma once
 
 #include <map>
 #include <vector>
@@ skipping 15 matching lines @@
 namespace browser_sync {
 
 class ChangeProcessor;
 class UIModelWorker;
 
 // A class to keep track of the workers and routing info for the
 // enabled sync types.
 class SyncBackendRegistrar : public ModelSafeWorkerRegistrar {
  public:
   // |initial_types| contains the initial set of types to sync
-  // (initially put in the passive group).  Does not take ownership of
-  // |profile| or |sync_loop|.  Must be created on the UI thread.
+  // (initially put in the passive group).  |name| is used for
+  // debugging.  Does not take ownership of |profile| or |sync_loop|.
+  // Must be created on the UI thread.
   SyncBackendRegistrar(const syncable::ModelTypeSet& initial_types,
+                       const std::string& name,
                        Profile* profile,
                        MessageLoop* sync_loop);
 
   // SyncBackendRegistrar must be destroyed as follows:
   //
   //   1) On the sync thread, call OnSyncerShutdownComplete() after
   //      the syncer is shutdown.
   //   2) Meanwhile, on the UI thread, call StopOnUIThread(), which
   //      blocks until OnSyncerShutdownComplete() is called.
   //   3) Destroy the SyncBackendRegistrar.
@@ skipping 52 matching lines @@
   // Must be called with |lock_| held.  Simply returns the change
   // processor for the given type, if it exists.  May be called from
   // any thread.
   ChangeProcessor* GetProcessorUnsafe(syncable::ModelType type);
 
   // Return true if |model_type| lives on the current thread.  Must be
   // called with |lock_| held.  May be called on any thread.
   bool IsCurrentThreadSafeForModel(
       syncable::ModelType model_type) const;
 
+  // Name used for debugging.
+  const std::string name_;
+
   Profile* const profile_;
 
   MessageLoop* const sync_loop_;
 
   const scoped_refptr<UIModelWorker> ui_worker_;
 
   bool stopped_on_ui_thread_;
 
   // Protects all variables below.
   mutable base::Lock lock_;
@@ skipping 13 matching lines @@
 
   // The change processors that handle the different data types.
   std::map<syncable::ModelType, ChangeProcessor*> processors_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendRegistrar);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_REGISTRAR_H_