sync: Make nudge + config jobs reliable in SyncerThread2

chrome/browser/sync/sessions/sync_session.cc

Index: chrome/browser/sync/sessions/sync_session.cc
diff --git a/chrome/browser/sync/sessions/sync_session.cc b/chrome/browser/sync/sessions/sync_session.cc
index cd01375d627e19dcf9dabc04a35970ddac393a92..bff0063c6a1f0dba9c0facab6f9ed3bf9a22c755 100644
--- a/chrome/browser/sync/sessions/sync_session.cc
+++ b/chrome/browser/sync/sessions/sync_session.cc
@@ -41,11 +41,14 @@ void SyncSession::Coalesce(const SyncSession& session) {
                  std::back_inserter(temp));
   workers_.swap(temp);
 
-  ModelSafeRoutingInfo temp_r;
-  std::set_union(routing_info_.begin(), routing_info_.end(),
-      session.routing_info_.begin(), session.routing_info_.end(),
-      std::insert_iterator<ModelSafeRoutingInfo>(temp_r, temp_r.begin()));
-  routing_info_.swap(temp_r);
+  // We have to update the model safe routing info to the union. In case the
+  // same key is present in both pick the one from session.
+  for (ModelSafeRoutingInfo::const_iterator it =
+       session.routing_info_.begin();
+       it != session.routing_info_.end();
+       it++) {
+    routing_info_[it->first] = it->second;
+  }
 }
 
 void SyncSession::ResetTransientState() {