chromium/ash/webui/personalization_app/resources/js/ambient/topic_source_list_element.html

<style include="common">
  topic-source-item {
    align-items: center;
    height: 64px;
    margin: 0 10px;
    width: calc(100% - 20px);
  }

  iron-list > *:not(:first-of-type) {
    border-top: var(--cr-separator-line);
  }

  iron-list > :focus {
    background-color: var(--cros-sys-hover_on_subtle, --cr-focused-item-color);
  }
</style>

<h3 id="topicSourceTitle" class="ambient-subpage-element-title">
  $i18n{ambientModeTopicSourceTitle}
</h3>

<iron-list id="topicSourceList" items="[[topicSources]]"
    aria-describedby="topicSourceTitle" role="radiogroup">
  <template>
    <topic-source-item topic-source="[[item]]"
        disabled="[[isTopicSourceDisabled_(item, selectedAmbientTheme)]]"
        role="radio"
        tabindex$="[[tabIndex]]"
        has-google-photos-albums="[[hasGooglePhotosAlbums]]"
        checked="[[isSelected_(item, selectedTopicSource)]]">
    </topic-source-item>
  </template>
</iron-list>