Sync: Don't set/use Parent ID for non-hierarchical sync data types.

sync/engine/syncer_util.cc

 // Copyright 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/syncer_util.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 388 matching lines @@
     } else {
       // Otherwise, fake a server version by bumping the local number.
       target->PutServerVersion(
           std::max(target->GetServerVersion(), target->GetBaseVersion()) + 1);
     }
     return;
   }
 
   DCHECK_EQ(target->GetId(), SyncableIdFromProto(update.id_string()))
       << "ID Changing not supported here";
-  target->PutServerParentId(SyncableIdFromProto(update.parent_id_string()));
+  if (SyncerProtoUtil::ShouldMaintainHierarchy(update)) {
+    target->PutServerParentId(SyncableIdFromProto(update.parent_id_string()));
+  } else {
+    target->PutServerParentId(syncable::Id());
+  }
   target->PutServerNonUniqueName(name);
   target->PutServerVersion(update.version());
   target->PutServerCtime(ProtoTimeToTime(update.ctime()));
   target->PutServerMtime(ProtoTimeToTime(update.mtime()));
   target->PutServerIsDir(IsFolder(update));
   if (update.has_server_defined_unique_tag()) {
     const std::string& tag = update.server_defined_unique_tag();
     target->PutUniqueServerTag(tag);
   }
   if (update.has_client_defined_unique_tag()) {
@@ skipping 251 matching lines @@
   if (update.version() < target->GetServerVersion()) {
     LOG(WARNING) << "Update older than current server version for "
                  << *target << " Update:"
                  << SyncerProtoUtil::SyncEntityDebugString(update);
     return VERIFY_SUCCESS;  // Expected in new sync protocol.
   }
   return VERIFY_UNDECIDED;
 }
 
 }  // namespace syncer