metadata.html

<x-meta id="google-map" label="Google Map">
  <template>
    <google-map style="width: 400px; height: 400px; display: block;"></google-map>
  </template>
  <property name="mapType" kind="select" options="roadmap,satellite,hybrid,terrain"></property>
  <template id="imports">
    <link rel="import" href="google-map.html">
  </template>
</x-meta>

<x-meta id="google-map-directions" label="Google Map Directions">
  <template>
    <google-map-directions></google-map-directions>
  </template>
  <property name="map" kind="string"></property>
  <property name="travelMode" kind="select" options="DRIVING,TRANSIT,WALKING,BICYCLING"></property>
  <template id="imports">
    <link rel="import" href="google-map-directions.html">
  </template>
</x-meta>

<x-meta id="google-map-search" label="Google Map Search">
  <template>
    <google-map-search></google-map-search>
  </template>
  <property name="map" kind="string"></property>
  <property name="query" kind="string"></property>
  <template id="imports">
    <link rel="import" href="google-map-search.html">
  </template>
</x-meta>