[Sync] Clean up ProfileSyncService observer events

sync/engine/sync_scheduler_impl.cc

 // Copyright (c) 2012 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 "sync/engine/sync_scheduler_impl.h"
 
 #include <algorithm>
 #include <cstring>
 
 #include "base/auto_reset.h"
@@ skipping 78 matching lines @@
     ModelTypeSet types_to_download,
     const ModelSafeRoutingInfo& routing_info,
     const base::Closure& ready_task,
     const base::Closure& retry_task)
     : source(source),
       types_to_download(types_to_download),
       routing_info(routing_info),
       ready_task(ready_task),
       retry_task(retry_task) {
   DCHECK(!ready_task.is_null());
-  DCHECK(!retry_task.is_null());
 }
 ConfigurationParams::~ConfigurationParams() {}
 
 SyncSchedulerImpl::WaitInterval::WaitInterval()
     : mode(UNKNOWN) {}
 
 SyncSchedulerImpl::WaitInterval::WaitInterval(Mode mode, TimeDelta length)
     : mode(mode), length(length) {}
 
 SyncSchedulerImpl::WaitInterval::~WaitInterval() {}
@@ skipping 800 matching lines @@
 
 #undef SDVLOG_LOC
 
 #undef SDVLOG
 
 #undef SLOG
 
 #undef ENUM_CASE
 
 }  // namespace syncer