sync: Make nudge + config jobs reliable in SyncerThread2

chrome/browser/sync/glue/sync_backend_host.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 "build/build_config.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 394 matching lines @@
   {
     base::AutoLock lock(registrar_lock_);
     pending_config_mode_state_.reset(
         MakePendingConfigModeState(data_type_controllers, types, ready_task,
                                    &registrar_.routing_info));
   }
 
   // If we're doing the first configure (at startup) this is redundant as the
   // syncer thread always must start in config mode.
   if (using_new_syncer_thread_) {
-    core_->syncapi()->StartConfigurationMode(NewCallback(core_.get(),
-        &SyncBackendHost::Core::FinishConfigureDataTypes));
+    core_thread_.message_loop()->PostTask(
+        FROM_HERE,
+        NewRunnableMethod(core_.get(),
+        &SyncBackendHost::Core::DoStartConfigurationMode));
   } else {
     FinishConfigureDataTypesOnFrontendLoop();
   }
 }
 
 void SyncBackendHost::FinishConfigureDataTypesOnFrontendLoop() {
   DCHECK_EQ(MessageLoop::current(), frontend_loop_);
   // Nudge the syncer. This is necessary for both datatype addition/deletion.
   //
   // Deletions need a nudge in order to ensure the deletion occurs in a timely
@@ skipping 777 matching lines @@
   syncapi_->RemoveObserver(&sync_manager_observer_);
 }
 
 void SyncBackendHost::Core::DoProcessMessage(
     const std::string& name, const JsArgList& args,
     const JsEventHandler* sender) {
   DCHECK_EQ(MessageLoop::current(), host_->core_thread_.message_loop());
   syncapi_->GetJsBackend()->ProcessMessage(name, args, sender);
 }
 
+void SyncBackendHost::Core::DoStartConfigurationMode() {
+  syncapi_->StartConfigurationMode(NewCallback(this,
+        &SyncBackendHost::Core::FinishConfigureDataTypes));
+}
+
 void SyncBackendHost::Core::DeferNudgeForCleanup() {
   DCHECK_EQ(MessageLoop::current(), host_->core_thread_.message_loop());
   deferred_nudge_for_cleanup_requested_ = true;
 }
 
 }  // namespace browser_sync