[Sync] Make BackendMigrator not wait for full sync cycles

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 <stddef.h>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 586 matching lines @@
   unrecoverable_error_location_.reset(
       new tracked_objects::Location(from_here.function_name(),
                                     from_here.file_name(),
                                     from_here.line_number(),
                                     from_here.program_counter()));
 
   // Tell the wizard so it can inform the user only if it is already open.
   wizard_.Step(SyncSetupWizard::FATAL_ERROR);
 
   NotifyObservers();
-  LOG(ERROR) << "Unrecoverable error detected -- ProfileSyncService unusable."
-      << message;
   std::string location;
   from_here.Write(true, true, &location);
-  LOG(ERROR) << location;
+  LOG(ERROR)
+      << "Unrecoverable error detected at " << location
+      << " -- ProfileSyncService unusable: " << message;
 
   // Shut all data types down.
   MessageLoop::current()->PostTask(FROM_HERE,
         scoped_runnable_method_factory_.NewRunnableMethod(
         &ProfileSyncService::Shutdown, true));
 }
 
 void ProfileSyncService::OnBackendInitialized(
     const WeakHandle<JsBackend>& js_backend, bool success) {
   if (!success) {
@@ skipping 952 matching lines @@
             *profile_->GetPrefs()->GetList(prefs::kAcknowledgedSyncTypes));
     syncable::ModelTypeSet registered;
     GetRegisteredDataTypes(&registered);
     syncable::ModelTypeBitSet registered_bit_set =
         syncable::ModelTypeBitSetFromSet(registered);
     unacknowledged = registered_bit_set & ~acknowledged;
   }
   return unacknowledged;
 }