Migrate GrDateFromatter to lit

 - Remove usage of TooltipMixin for GrDateFormatter
 - Migrate GrDateFromatter to Lit
 - Use a gr-tooltip-component inside of gr-date-formatter when
 necessary.

Change-Id: I45766e9775383612a19b64692b15e5865164f25f
diff --git a/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log.ts b/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log.ts
index 941a09a..6605350 100644
--- a/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log.ts
+++ b/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log.ts
@@ -17,7 +17,6 @@
 
 import '../../../styles/gr-table-styles';
 import '../../../styles/shared-styles';
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import '../../shared/gr-account-link/gr-account-link';
 import {PolymerElement} from '@polymer/polymer/polymer-element';
 import {htmlTemplate} from './gr-group-audit-log_html';
diff --git a/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log_html.ts b/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log_html.ts
index 40c2f30..828aa55 100644
--- a/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-group-audit-log/gr-group-audit-log_html.ts
@@ -43,7 +43,7 @@
       <template is="dom-repeat" items="[[_auditLog]]">
         <tr class="table">
           <td class="date">
-            <gr-date-formatter has-tooltip="" date-str="[[item.date]]">
+            <gr-date-formatter withTooltip date-str="[[item.date]]">
             </gr-date-formatter>
           </td>
           <td class="type">[[itemType(item.type)]]</td>
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-detail-list/gr-repo-detail-list_html.ts b/polygerrit-ui/app/elements/admin/gr-repo-detail-list/gr-repo-detail-list_html.ts
index 4f66f0d..429a6d6 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-detail-list/gr-repo-detail-list_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-detail-list/gr-repo-detail-list_html.ts
@@ -145,10 +145,7 @@
             <td class$="tagger [[_hideIfBranch(detailType)]]">
               <div class$="tagger [[_computeHideTagger(item.tagger)]]">
                 <gr-account-link account="[[item.tagger]]"> </gr-account-link>
-                (<gr-date-formatter
-                  has-tooltip=""
-                  date-str="[[item.tagger.date]]"
-                >
+                (<gr-date-formatter withTooltip date-str="[[item.tagger.date]]">
                 </gr-date-formatter
                 >)
               </div>
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_html.ts b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_html.ts
index 4557aac..1b47791 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_html.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_html.ts
@@ -253,7 +253,7 @@
     hidden$="[[isColumnHidden('Updated', visibleChangeTableColumns)]]"
   >
     <gr-date-formatter
-      has-tooltip=""
+      withTooltip
       date-str="[[_formatDate(change.updated)]]"
     ></gr-date-formatter>
   </td>
@@ -262,7 +262,7 @@
     hidden$="[[isColumnHidden('Submitted', visibleChangeTableColumns)]]"
   >
     <gr-date-formatter
-      has-tooltip=""
+      withTooltip
       date-str="[[_formatDate(change.submitted)]]"
     ></gr-date-formatter>
   </td>
@@ -271,9 +271,9 @@
     hidden$="[[isColumnHidden('Waiting', visibleChangeTableColumns)]]"
   >
     <gr-date-formatter
-      has-tooltip=""
-      force-relative=""
-      relative-option-no-ago=""
+      withTooltip
+      forceRelative
+      relativeOptionNoAge
       date-str="[[_computeWaiting(account, change)]]"
     ></gr-date-formatter>
   </td>
diff --git a/polygerrit-ui/app/elements/change-list/gr-repo-header/gr-repo-header.ts b/polygerrit-ui/app/elements/change-list/gr-repo-header/gr-repo-header.ts
index beadea3..9242a58 100644
--- a/polygerrit-ui/app/elements/change-list/gr-repo-header/gr-repo-header.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-repo-header/gr-repo-header.ts
@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import {GerritNav} from '../../core/gr-navigation/gr-navigation';
 import {RepoName} from '../../../types/common';
 import {WebLinkInfo} from '../../../types/diff';
diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_html.ts b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_html.ts
index c080345..c105aaa 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_html.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_html.ts
@@ -134,9 +134,9 @@
         <span class="title">Submitted</span>
         <span class="value">
           <gr-date-formatter
-            has-tooltip=""
+            withTooltip
             date-str="[[change.submitted]]"
-            show-yesterday=""
+            showYesterday=""
           ></gr-date-formatter>
         </span>
       </section>
@@ -154,9 +154,9 @@
       </span>
       <span class="value">
         <gr-date-formatter
-          has-tooltip=""
+          withTooltip
           date-str="[[change.updated]]"
-          show-yesterday=""
+          showYesterday
         ></gr-date-formatter>
       </span>
     </section>
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index ced66a9..ed9820f 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -24,7 +24,6 @@
 import '../../shared/gr-button/gr-button';
 import '../../shared/gr-change-star/gr-change-star';
 import '../../shared/gr-change-status/gr-change-status';
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import '../../shared/gr-editable-content/gr-editable-content';
 import '../../shared/gr-linked-text/gr-linked-text';
 import '../../shared/gr-overlay/gr-overlay';
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.js b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.js
index 5def25a..4acf245 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.js
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.js
@@ -17,6 +17,7 @@
 
 import '../../../test/common-test-setup-karma.js';
 import '../../diff/gr-comment-api/gr-comment-api.js';
+import '../../shared/gr-date-formatter/gr-date-formatter.js';
 import {getMockDiffResponse} from '../../../test/mocks/diff-response.js';
 import './gr-file-list.js';
 import {createCommentApiMockWithTemplateElement} from '../../../test/mocks/comment-api.js';
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
index ddbd22e..c9680ef 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
@@ -325,8 +325,8 @@
         <template is="dom-if" if="[[!message.id]]">
           <span class="date">
             <gr-date-formatter
-              has-tooltip=""
-              show-date-and-time=""
+              withTooltip
+              showDateAndTime
               date-str="[[message.date]]"
             ></gr-date-formatter>
           </span>
@@ -334,8 +334,8 @@
         <template is="dom-if" if="[[message.id]]">
           <span class="date" on-click="_handleAnchorClick">
             <gr-date-formatter
-              has-tooltip=""
-              show-date-and-time=""
+              withTooltip
+              showDateAndTime
               date-str="[[message.date]]"
             ></gr-date-formatter>
           </span>
diff --git a/polygerrit-ui/app/elements/settings/gr-account-info/gr-account-info_html.ts b/polygerrit-ui/app/elements/settings/gr-account-info/gr-account-info_html.ts
index 514f00e..51259c8 100644
--- a/polygerrit-ui/app/elements/settings/gr-account-info/gr-account-info_html.ts
+++ b/polygerrit-ui/app/elements/settings/gr-account-info/gr-account-info_html.ts
@@ -56,7 +56,7 @@
       <span class="title">Registered</span>
       <span class="value">
         <gr-date-formatter
-          has-tooltip=""
+          withTooltip
           date-str="[[_account.registered_on]]"
         ></gr-date-formatter>
       </span>
diff --git a/polygerrit-ui/app/elements/settings/gr-change-table-editor/gr-change-table-editor.ts b/polygerrit-ui/app/elements/settings/gr-change-table-editor/gr-change-table-editor.ts
index b79e448..d8e43ce 100644
--- a/polygerrit-ui/app/elements/settings/gr-change-table-editor/gr-change-table-editor.ts
+++ b/polygerrit-ui/app/elements/settings/gr-change-table-editor/gr-change-table-editor.ts
@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 import '../../shared/gr-button/gr-button';
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import '../../../styles/shared-styles';
 import '../../../styles/gr-form-styles';
 import {dom, EventApi} from '@polymer/polymer/lib/legacy/polymer.dom';
diff --git a/polygerrit-ui/app/elements/settings/gr-menu-editor/gr-menu-editor.ts b/polygerrit-ui/app/elements/settings/gr-menu-editor/gr-menu-editor.ts
index ace1e1a..4096b02 100644
--- a/polygerrit-ui/app/elements/settings/gr-menu-editor/gr-menu-editor.ts
+++ b/polygerrit-ui/app/elements/settings/gr-menu-editor/gr-menu-editor.ts
@@ -16,7 +16,6 @@
  */
 import '@polymer/iron-input/iron-input';
 import '../../shared/gr-button/gr-button';
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import '../../../styles/shared-styles';
 import '../../../styles/gr-form-styles';
 import {dom, EventApi} from '@polymer/polymer/lib/legacy/polymer.dom';
diff --git a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
index da4bb0a..de84eae 100644
--- a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
+++ b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
@@ -29,7 +29,6 @@
 import '../gr-change-table-editor/gr-change-table-editor';
 import '../../shared/gr-button/gr-button';
 import {GrButton} from '../../shared/gr-button/gr-button';
-import '../../shared/gr-date-formatter/gr-date-formatter';
 import '../../shared/gr-diff-preferences/gr-diff-preferences';
 import '../../shared/gr-page-nav/gr-page-nav';
 import '../../shared/gr-select/gr-select';
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
index 418cd0e..b214be0 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -20,7 +20,6 @@
 import '../../plugins/gr-endpoint-param/gr-endpoint-param';
 import '../gr-button/gr-button';
 import '../gr-dialog/gr-dialog';
-import '../gr-date-formatter/gr-date-formatter';
 import '../gr-formatted-text/gr-formatted-text';
 import '../gr-icons/gr-icons';
 import '../gr-overlay/gr-overlay';
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_html.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_html.ts
index b00bf8b..4cb7738 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_html.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_html.ts
@@ -313,7 +313,7 @@
       <template is="dom-if" if="[[comment.updated]]">
         <span class="date" tabindex="0" on-click="_handleAnchorClick">
           <gr-date-formatter
-            has-tooltip=""
+            withTooltip
             date-str="[[comment.updated]]"
           ></gr-date-formatter>
         </span>
diff --git a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter.ts b/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter.ts
index 437e7e8..99f9265 100644
--- a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter.ts
+++ b/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter.ts
@@ -14,11 +14,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import '../../../styles/shared-styles';
-import {PolymerElement} from '@polymer/polymer/polymer-element';
-import {htmlTemplate} from './gr-date-formatter_html';
-import {TooltipMixin} from '../../../mixins/gr-tooltip-mixin/gr-tooltip-mixin';
-import {property, customElement} from '@polymer/decorators';
+import '../gr-tooltip-content/gr-tooltip-content';
+import {css, html, LitElement} from 'lit';
+import {customElement, property} from 'lit/decorators';
 import {
   parseDate,
   fromNow,
@@ -75,16 +73,9 @@
   }
 }
 
-// This avoids JSC_DYNAMIC_EXTENDS_WITHOUT_JSDOC closure compiler error.
-const base = TooltipMixin(PolymerElement);
-
 @customElement('gr-date-formatter')
-export class GrDateFormatter extends base {
-  static get template() {
-    return htmlTemplate;
-  }
-
-  @property({type: String, notify: true})
+export class GrDateFormatter extends LitElement {
+  @property({type: String})
   dateStr: string | undefined = undefined;
 
   @property({type: Boolean})
@@ -95,30 +86,20 @@
    * native browser tooltip.
    */
   @property({type: Boolean})
-  override hasTooltip = false;
+  withTooltip = false;
 
   @property({type: Boolean})
   showYesterday = false;
 
-  /**
-   * The title to be used as the native tooltip or by the tooltip behavior.
-   */
-  @property({
-    type: String,
-    reflectToAttribute: true,
-    computed: '_computeFullDateStr(dateStr, _timeFormat, _dateFormat)',
-  })
-  override title = '';
-
   /** @type {?{short: string, full: string}} */
   @property({type: Object})
-  _dateFormat?: DateFormatPair;
+  private dateFormat?: DateFormatPair;
 
   @property({type: String})
-  _timeFormat?: string;
+  private timeFormat?: string;
 
   @property({type: Boolean})
-  _relative = false;
+  private relative = false;
 
   @property({type: Boolean})
   forceRelative = false;
@@ -132,76 +113,110 @@
     super();
   }
 
+  static override get styles() {
+    return [
+      css`
+        host {
+          color: inherit;
+          display: inline;
+        }
+      `,
+    ];
+  }
+
+  override render() {
+    if (!this.withTooltip) {
+      return this.renderDateString();
+    }
+
+    const fullDateStr = this.computeFullDateStr();
+    if (!fullDateStr) {
+      return this.renderDateString();
+    }
+    return html`
+      <gr-tooltip-content has-tooltip title=${fullDateStr}>
+        ${this.renderDateString()}
+      </gr-tooltip-content>
+    `;
+  }
+
+  private renderDateString() {
+    return html` <span>${this._computeDateStr()}</span>`;
+  }
+
   override connectedCallback() {
     super.connectedCallback();
     this._loadPreferences();
   }
 
+  // private but used by tests
   _getUtcOffsetString() {
     return utcOffsetString();
   }
 
+  // private but used by tests
   _loadPreferences() {
     return this._getLoggedIn().then(loggedIn => {
       if (!loggedIn) {
-        this._timeFormat = TimeFormats.TIME_24;
-        this._dateFormat = DateFormats.STD;
-        this._relative = this.forceRelative;
+        this.timeFormat = TimeFormats.TIME_24;
+        this.dateFormat = DateFormats.STD;
+        this.relative = this.forceRelative;
         return;
       }
-      return Promise.all([this._loadTimeFormat(), this._loadRelative()]);
+      return Promise.all([this._loadTimeFormat(), this.loadRelative()]);
     });
   }
 
+  // private but used in gr/file-list_test.js
   _loadTimeFormat() {
-    return this._getPreferences().then(preferences => {
+    return this.getPreferences().then(preferences => {
       if (!preferences) {
         throw Error('Preferences is not set');
       }
-      this._decideTimeFormat(preferences.time_format);
-      this._decideDateFormat(preferences.date_format);
+      this.decideTimeFormat(preferences.time_format);
+      this.decideDateFormat(preferences.date_format);
     });
   }
 
-  _decideTimeFormat(timeFormat: TimeFormat) {
+  private decideTimeFormat(timeFormat: TimeFormat) {
     switch (timeFormat) {
       case TimeFormat.HHMM_12:
-        this._timeFormat = TimeFormats.TIME_12;
+        this.timeFormat = TimeFormats.TIME_12;
         break;
       case TimeFormat.HHMM_24:
-        this._timeFormat = TimeFormats.TIME_24;
+        this.timeFormat = TimeFormats.TIME_24;
         break;
       default:
         assertNever(timeFormat, `Invalid time format: ${timeFormat}`);
     }
   }
 
-  _decideDateFormat(dateFormat: DateFormat) {
+  private decideDateFormat(dateFormat: DateFormat) {
     switch (dateFormat) {
       case DateFormat.STD:
-        this._dateFormat = DateFormats.STD;
+        this.dateFormat = DateFormats.STD;
         break;
       case DateFormat.US:
-        this._dateFormat = DateFormats.US;
+        this.dateFormat = DateFormats.US;
         break;
       case DateFormat.ISO:
-        this._dateFormat = DateFormats.ISO;
+        this.dateFormat = DateFormats.ISO;
         break;
       case DateFormat.EURO:
-        this._dateFormat = DateFormats.EURO;
+        this.dateFormat = DateFormats.EURO;
         break;
       case DateFormat.UK:
-        this._dateFormat = DateFormats.UK;
+        this.dateFormat = DateFormats.UK;
         break;
       default:
         assertNever(dateFormat, `Invalid date format: ${dateFormat}`);
     }
   }
 
-  _loadRelative() {
-    return this._getPreferences().then(prefs => {
+  private loadRelative() {
+    return this.getPreferences().then(prefs => {
       // prefs.relative_date_in_change_table is not set when false.
-      this._relative =
+      this.relative =
         this.forceRelative || !!(prefs && prefs.relative_date_in_change_table);
     });
   }
@@ -210,70 +225,60 @@
     return this.restApiService.getLoggedIn();
   }
 
-  _getPreferences() {
+  private getPreferences() {
     return this.restApiService.getPreferences();
   }
 
-  _computeDateStr(
-    dateStr?: Timestamp,
-    timeFormat?: string,
-    dateFormat?: DateFormatPair,
-    relative?: boolean,
-    showDateAndTime?: boolean,
-    showYesterday?: boolean
-  ) {
-    if (!dateStr || !timeFormat || !dateFormat) {
+  // private but used by tests
+  _computeDateStr() {
+    if (!this.dateStr || !this.timeFormat || !this.dateFormat) {
       return '';
     }
-    const date = parseDate(dateStr);
+    const date = parseDate(this.dateStr as Timestamp);
     if (!isValidDate(date)) {
       return '';
     }
-    if (relative) {
+    if (this.relative) {
       return fromNow(date, this.relativeOptionNoAgo);
     }
     const now = new Date();
-    let format = dateFormat.full;
+    let format = this.dateFormat.full;
     if (isWithinDay(now, date)) {
-      format = timeFormat;
-    } else if (showYesterday && wasYesterday(now, date)) {
-      return `Yesterday at ${formatDate(date, timeFormat)}`;
+      format = this.timeFormat;
+    } else if (this.showYesterday && wasYesterday(now, date)) {
+      return `Yesterday at ${formatDate(date, this.timeFormat)}`;
     } else {
       if (isWithinHalfYear(now, date)) {
-        format = dateFormat.short;
+        format = this.dateFormat.short;
       }
-      if (this.showDateAndTime || showDateAndTime) {
-        format = `${format} ${timeFormat}`;
+      if (this.showDateAndTime || this.showDateAndTime) {
+        format = `${format} ${this.timeFormat}`;
       }
     }
     return formatDate(date, format);
   }
 
-  _timeToSecondsFormat(timeFormat: string | undefined) {
-    return timeFormat === TimeFormats.TIME_12
-      ? TimeFormats.TIME_12_WITH_SEC
-      : TimeFormats.TIME_24_WITH_SEC;
-  }
-
-  _computeFullDateStr(
-    dateStr?: Timestamp,
-    timeFormat?: string,
-    dateFormat?: DateFormatPair
-  ) {
+  private computeFullDateStr() {
     // Polymer 2: check for undefined
-    if ([dateStr, timeFormat].includes(undefined) || !dateFormat) {
+    if (
+      [this.dateStr, this.timeFormat].includes(undefined) ||
+      !this.dateFormat
+    ) {
       return undefined;
     }
 
-    if (!dateStr) {
+    if (!this.dateStr) {
       return '';
     }
-    const date = parseDate(dateStr);
+    const date = parseDate(this.dateStr as Timestamp);
     if (!isValidDate(date)) {
       return '';
     }
-    let format = dateFormat.full + ', ';
-    format += this._timeToSecondsFormat(timeFormat);
+    let format = this.dateFormat.full + ', ';
+    format +=
+      this.timeFormat === TimeFormats.TIME_12
+        ? TimeFormats.TIME_12_WITH_SEC
+        : TimeFormats.TIME_24_WITH_SEC;
     return formatDate(date, format) + this._getUtcOffsetString();
   }
 }
diff --git a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_html.ts b/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_html.ts
deleted file mode 100644
index 4808832..0000000
--- a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_html.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-/**
- * @license
- * Copyright (C) 2020 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-import {html} from '@polymer/polymer/lib/utils/html-tag';
-
-export const htmlTemplate = html`
-  <style>
-    :host {
-      color: inherit;
-      display: inline;
-    }
-  </style>
-  <span>
-    [[_computeDateStr(dateStr, _timeFormat, _dateFormat, _relative,
-    showDateAndTime, showYesterday)]]
-  </span>
-`;
diff --git a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_test.js b/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_test.js
index 9a96c2d..860a7e7 100644
--- a/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_test.js
+++ b/polygerrit-ui/app/elements/shared/gr-date-formatter/gr-date-formatter_test.js
@@ -22,14 +22,18 @@
 import {stubRestApi} from '../../../test/test-utils.js';
 
 const basicFixture = fixtureFromTemplate(html`
-<gr-date-formatter date-str="2015-09-24 23:30:17.033000000"></gr-date-formatter>
+<gr-date-formatter withTooltip dateStr="2015-09-24 23:30:17.033000000">
+</gr-date-formatter>
+`);
+
+const lightFixture = fixtureFromTemplate(html`
+<gr-date-formatter dateStr="2015-09-24 23:30:17.033000000"></gr-date-formatter>
 `);
 
 suite('gr-date-formatter tests', () => {
   let element;
 
   setup(() => {
-
   });
 
   /**
@@ -41,7 +45,7 @@
     return d;
   }
 
-  function testDates(nowStr, dateStr, expected, expectedWithDateAndTime,
+  async function testDates(nowStr, dateStr, expected, expectedWithDateAndTime,
       expectedTooltip) {
     // Normalize and convert the date to mimic server response.
     dateStr = normalizedDate(dateStr)
@@ -50,13 +54,13 @@
         .slice(0, -1);
     sinon.useFakeTimers(normalizedDate(nowStr).getTime());
     element.dateStr = dateStr;
-    flush();
-    const span = element.shadowRoot
-        .querySelector('span');
+    await element.updateComplete;
+    const span = element.shadowRoot.querySelector('span');
+    const tooltip = element.shadowRoot.querySelector('gr-tooltip-content');
     assert.equal(span.textContent.trim(), expected);
-    assert.equal(element.title, expectedTooltip);
+    assert.equal(tooltip.title, expectedTooltip);
     element.showDateAndTime = true;
-    flush();
+    await element.updateComplete;
     assert.equal(span.textContent.trim(), expectedWithDateAndTime);
   }
 
@@ -81,35 +85,37 @@
 
     test('invalid dates are quietly rejected', () => {
       assert.notOk((new Date('foo')).valueOf());
-      assert.equal(element._computeDateStr('foo', 'h:mm A'), '');
+      element.dateStr = 'foo';
+      element.timeFormat = 'h:mm A';
+      assert.equal(element._computeDateStr(), '');
     });
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '15:34',
           '15:34',
           'Jul 29, 2015, 15:34:14');
     });
 
-    test('Within 24 hours on different days', () => {
-      testDates('2015-07-29 03:34:14.985000000',
+    test('Within 24 hours on different days', async () => {
+      await testDates('2015-07-29 03:34:14.985000000',
           '2015-07-28 20:25:14.985000000',
           'Jul 28',
           'Jul 28 20:25',
           'Jul 28, 2015, 20:25:14');
     });
 
-    test('More than 24 hours but less than six months', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('More than 24 hours but less than six months', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-06-15 03:25:14.985000000',
           'Jun 15',
           'Jun 15 03:25',
           'Jun 15, 2015, 03:25:14');
     });
 
-    test('More than six months', () => {
-      testDates('2015-09-15 20:34:00.000000000',
+    test('More than six months', async () => {
+      await testDates('2015-09-15 20:34:00.000000000',
           '2015-01-15 03:25:00.000000000',
           'Jan 15, 2015',
           'Jan 15, 2015 03:25',
@@ -128,24 +134,24 @@
       return element._loadPreferences();
     }));
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '15:34',
           '15:34',
           '07/29/15, 15:34:14');
     });
 
-    test('Within 24 hours on different days', () => {
-      testDates('2015-07-29 03:34:14.985000000',
+    test('Within 24 hours on different days', async () => {
+      await testDates('2015-07-29 03:34:14.985000000',
           '2015-07-28 20:25:14.985000000',
           '07/28',
           '07/28 20:25',
           '07/28/15, 20:25:14');
     });
 
-    test('More than 24 hours but less than six months', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('More than 24 hours but less than six months', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-06-15 03:25:14.985000000',
           '06/15',
           '06/15 03:25',
@@ -164,24 +170,24 @@
       return element._loadPreferences();
     }));
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '15:34',
           '15:34',
           '2015-07-29, 15:34:14');
     });
 
-    test('Within 24 hours on different days', () => {
-      testDates('2015-07-29 03:34:14.985000000',
+    test('Within 24 hours on different days', async () => {
+      await testDates('2015-07-29 03:34:14.985000000',
           '2015-07-28 20:25:14.985000000',
           '07-28',
           '07-28 20:25',
           '2015-07-28, 20:25:14');
     });
 
-    test('More than 24 hours but less than six months', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('More than 24 hours but less than six months', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-06-15 03:25:14.985000000',
           '06-15',
           '06-15 03:25',
@@ -200,24 +206,24 @@
       return element._loadPreferences();
     }));
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '15:34',
           '15:34',
           '29.07.2015, 15:34:14');
     });
 
-    test('Within 24 hours on different days', () => {
-      testDates('2015-07-29 03:34:14.985000000',
+    test('Within 24 hours on different days', async () => {
+      await testDates('2015-07-29 03:34:14.985000000',
           '2015-07-28 20:25:14.985000000',
           '28. Jul',
           '28. Jul 20:25',
           '28.07.2015, 20:25:14');
     });
 
-    test('More than 24 hours but less than six months', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('More than 24 hours but less than six months', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-06-15 03:25:14.985000000',
           '15. Jun',
           '15. Jun 03:25',
@@ -236,24 +242,24 @@
       return element._loadPreferences();
     }));
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '15:34',
           '15:34',
           '29/07/2015, 15:34:14');
     });
 
-    test('Within 24 hours on different days', () => {
-      testDates('2015-07-29 03:34:14.985000000',
+    test('Within 24 hours on different days', async () => {
+      await testDates('2015-07-29 03:34:14.985000000',
           '2015-07-28 20:25:14.985000000',
           '28/07',
           '28/07 20:25',
           '28/07/2015, 20:25:14');
     });
 
-    test('More than 24 hours but less than six months', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('More than 24 hours but less than six months', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-06-15 03:25:14.985000000',
           '15/06',
           '15/06 03:25',
@@ -273,8 +279,8 @@
       })
     );
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '3:34 PM',
           '3:34 PM',
@@ -294,8 +300,8 @@
       })
     );
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '3:34 PM',
           '3:34 PM',
@@ -315,8 +321,8 @@
       })
     );
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '3:34 PM',
           '3:34 PM',
@@ -336,8 +342,8 @@
       })
     );
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '3:34 PM',
           '3:34 PM',
@@ -357,8 +363,8 @@
       })
     );
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '3:34 PM',
           '3:34 PM',
@@ -377,16 +383,16 @@
       return element._loadPreferences();
     }));
 
-    test('Within 24 hours on same day', () => {
-      testDates('2015-07-29 20:34:14.985000000',
+    test('Within 24 hours on same day', async () => {
+      await testDates('2015-07-29 20:34:14.985000000',
           '2015-07-29 15:34:14.985000000',
           '5 hours ago',
           '5 hours ago',
           'Jul 29, 2015, 3:34:14 PM');
     });
 
-    test('More than six months', () => {
-      testDates('2015-09-15 20:34:00.000000000',
+    test('More than six months', async () => {
+      await testDates('2015-09-15 20:34:00.000000000',
           '2015-01-15 03:25:00.000000000',
           '8 months ago',
           '8 months ago',
@@ -405,10 +411,10 @@
     }));
 
     test('Preferences are respected', () => {
-      assert.equal(element._timeFormat, 'h:mm A');
-      assert.equal(element._dateFormat.short, 'MM/DD');
-      assert.equal(element._dateFormat.full, 'MM/DD/YY');
-      assert.isTrue(element._relative);
+      assert.equal(element.timeFormat, 'h:mm A');
+      assert.equal(element.dateFormat.short, 'MM/DD');
+      assert.equal(element.dateFormat.full, 'MM/DD/YY');
+      assert.isTrue(element.relative);
     });
   });
 
@@ -419,10 +425,38 @@
     }));
 
     test('Default preferences are respected', () => {
-      assert.equal(element._timeFormat, 'HH:mm');
-      assert.equal(element._dateFormat.short, 'MMM DD');
-      assert.equal(element._dateFormat.full, 'MMM DD, YYYY');
-      assert.isFalse(element._relative);
+      assert.equal(element.timeFormat, 'HH:mm');
+      assert.equal(element.dateFormat.short, 'MMM DD');
+      assert.equal(element.dateFormat.full, 'MMM DD, YYYY');
+      assert.isFalse(element.relative);
+    });
+  });
+
+  suite('with tooltip', () => {
+    setup(async () => {
+      await stubRestAPI(null);
+      element = basicFixture.instantiate();
+      await element._loadPreferences();
+      await element.updateComplete;
+    });
+
+    test('Tooltip is present', () => {
+      const tooltip = element.shadowRoot.querySelector('gr-tooltip-content');
+      assert.isOk(tooltip);
+    });
+  });
+
+  suite('without tooltip', () => {
+    setup(async () => {
+      await stubRestAPI(null);
+      element = lightFixture.instantiate();
+      await element._loadPreferences();
+      await element.updateComplete;
+    });
+
+    test('Tooltip is absent', () => {
+      const tooltip = element.shadowRoot.querySelector('gr-tooltip-content');
+      assert.isNotOk(tooltip);
     });
   });
 });
diff --git a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account_html.ts b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account_html.ts
index f1f6bf8..076553b 100644
--- a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account_html.ts
+++ b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account_html.ts
@@ -128,7 +128,7 @@
             <span class="value">[[_computeReason(change)]]</span>
             <template is="dom-if" if="[[_computeLastUpdate(change)]]">
               (<gr-date-formatter
-                has-tooltip
+                withTooltip
                 date-str="[[_computeLastUpdate(change)]]"
               ></gr-date-formatter
               >)