sync: Process 'control' data separately

sync/engine/resolve_conflicts_command.cc

Index: sync/engine/resolve_conflicts_command.cc
diff --git a/sync/engine/resolve_conflicts_command.cc b/sync/engine/resolve_conflicts_command.cc
index edef3ff6f22fb965286d8ba56ee94124e4502db4..c9821be7ff2b55d50ee9c9d77d3b745df213b6d6 100644
--- a/sync/engine/resolve_conflicts_command.cc
+++ b/sync/engine/resolve_conflicts_command.cc
@@ -17,7 +17,13 @@ ResolveConflictsCommand::~ResolveConflictsCommand() {}
 
 std::set<ModelSafeGroup> ResolveConflictsCommand::GetGroupsToChange(
     const sessions::SyncSession& session) const {
-  return session.GetEnabledGroupsWithConflicts();
+  std::set<ModelSafeGroup> groups_with_conflicts =
+      session.GetEnabledGroupsWithConflicts();
+
+  // GROUP_CONTROL conflicts are not handled by this command.
+  groups_with_conflicts.erase(GROUP_CONTROL);
+
+  return groups_with_conflicts;
 }
 
 SyncerError ResolveConflictsCommand::ModelChangingExecuteImpl(