How to remove 'autocomplete disabled' from input field

I have a field in which the user is ask to input a year. My html looks like this

<div class="form-group {% if form_search2.year_search.errors %} error {% endif %}" style="padding: 0px;">
    <label class="col-xs-3 col-sm-2 control-label">{{ form_search2.year_search.label }}</label>
    <div class="col-xs-6" style="max-width:320px;display: inline;">
                            {{ form_search2.year_search(class='form-control', style="max-width: 300px;", placeholder="e.g. 1996-2001", autocomplete="on", type="text") }}
    </div>
    <div class="col-xs-3" style="display: inline;">
    </div>
</div>

with the form defined as

year_search = TextField("Year:")

when I look at this form in the browser (Chrome) I get the message

Automatic credit card filling is disabled because this form does not use a secure connection

How can I get rid of this? I have other fields which are defined in the same why, but they remember what has been typed before and help the user by suggesting old inputs.