nd when the current page change.
The page is send in event detail.
            </dd>
            <dt id="path_changed_event" class="constant">
                <span class="top-level-variable-type">String</span>
                <span class="name "><a href="polymer_app_layout/PolymerRouteBehavior/path_changed_event.html">path_changed_event</a></span>
                =
                <span class="constant-value">"current-path-changed"</span>
            </dt>
            <dd>
                <div class="is-co