src/main/resources/static/chromium-behavior.html

<dom-module id="common">
  <script>
    // Common constants and helper functions used by multiple behaviors below.
    let PLUGIN = null;
    const AUTOSUBMIT_LABEL = 'Auto-Submit';
    const AS_LABEL_MAX_VALUE = 1;
    const REVIEW_LABEL = 'Code-Review';
    const REVIEW_LABEL_MAX_VALUE = 1;
    const CQ_LABEL = 'Commit-Queue';
    const CQ_LABEL_MAX_VALUE = 2;
    const STATUS_SUBMITTED = 'MERGED';

    // Constants used by the AutoSubmit behaviors below.
    let AUTOSUBMIT_POPUP = null;
    let CUSTOM_QUICK_APPROVE_KEY = null;
    // Below are set in installAutoSubmit function.
    let _APPROVED_BY_ALL_OTHER_REVIEWERS = false;
    let _REVIEW_LABEL_MAX_VALUE = 0;
    let _CQ_LABEL_MAX_VALUE = 0;

    /**
     * Calls the server to get an updated change obj and returns its promise.
     */
    const getChangeObj = function() {
      const changeNum = PLUGIN.changeActions()._el.changeNum;
      var  url = '/changes/' + changeNum + '/detail';
      return PLUGIN.restApi().get(url);
    };

    /**
     * Calls the server to get list of of all draft comments that below to the
     * calling user.
     */
    const getChangeDrafts = function() {
      const changeNum = PLUGIN.changeActions()._el.changeNum;
      var  url = '/changes/' + changeNum + '/drafts';
      return PLUGIN.restApi().get(url);
    };

    /**
     * Returns the specified label from the change if it exists else [] is
     * returned.
     * @param {object} change gr-change-view
     * @param {string} labelName: The name of the label we want
     * @returns {object} gr-change-view.label
     */
    const getChangeLabel = function(change, labelName) {
      return change.labels[labelName] || [];
    };

    /**
     * Returns whether the specified vote is permitted on the label.
     * @param {object} change gr-change-view
     * @param {string} labelName: The name of the label we want to check
     * @param {string} vote: The vote we will check (e.g. '+2')
     * @returns {boolean}
     */
    const isLabelVotePermitted = function(change, labelName, vote) {
      const permitted = change.permitted_labels[labelName] || [];
      return permitted.indexOf(vote) !== -1;
    };

    /**
     * Checks whether the specified label and max value exist on the change.
     * @param {object} change gr-change-view
     * @param {string} labelName: The name of the label we want to check
     * @param {int} maxValue: The max value of the label we want to confirm.
     * @returns {boolean}
     */
    const checkLabelAndMaxValue = function(change, labelName, maxValue) {
      if (!change.labels[labelName] || !change.labels[labelName].values) {
        return false;
      }
      return maxValue === getLabelMaxValue(change, labelName);
    };

    /**
     * Returns the max value of the specified label. Returns 0 if the label
     * cannot be found or if it has no values.
     * @param {object} change gr-change-view
     * @param {string} labelName: The name of the label we want to check
     * @returns {boolean}
     */
    const getLabelMaxValue = function(change, labelName) {
      if (!change.labels[labelName] || !change.labels[labelName].values) {
        return 0;
      }
      return Math.max(...Object.keys(change.labels[labelName].values));
    };

    /**
     * Sets CR+1 and optionally CQ+2 on the current change.
     * @param {bool} sendToCQ: Whether the change should also be sent to the CQ.
     * @returns {promise} Promise from the POST call.
     */
    const setApprovalLabels = function(sendToCQ) {
      // TODO(rmistry): Add getChangeNum to GrChangeActionsInterface?
      const changeNum = PLUGIN.changeActions()._el.changeNum;
      var url = '/changes/' + changeNum + '/revisions/current/review';
      var body = {labels: {}};
      body['labels'][REVIEW_LABEL] = '+' + _REVIEW_LABEL_MAX_VALUE;
      body['drafts'] = 'PUBLISH';
      if (sendToCQ) {
        body['labels'][CQ_LABEL] = '+' + _CQ_LABEL_MAX_VALUE;
      }
      let changeActions = PLUGIN.changeActions();
      return PLUGIN.restApi().post(url, body).then(function() {
        // TODO(agable): Use real plugin API to reload change when
        // available. See
        // https://bugs.chromium.org/p/gerrit/issues/detail?id=6689
        changeActions._el.dispatchEvent(new CustomEvent(
            'reload-change',
            {detail: {action: 'reload-change'}, bubbles: false}));
      }.bind(this)).catch(function(err) {
        changeActions._el.dispatchEvent(new CustomEvent('show-alert',
            {detail: {message: err}, bubbles: true}));
        throw err;
      });
    };

    /**
     * Parses git trailers (and Rietveld tags) from a commit description.
     * @param {string} message: the commit message to parse
     * @param {string} token: the LHS of the trailer to parse (e.g. 'Bug')
     * @returns {string} all found trailers in normalized form (e.g. 'Bug: 1')
     */
    const getTrailer = function(message, token) {
      // TODO(agable): Remove support for parsing CAPS= style tags.
      var caps = token.replace(/-/g, '_').toUpperCase();
      var trailerRegexp = new RegExp(
        `^[ \t]*((${token}:|${caps}=)[ \t]*(.*))$`, 'gm');
      var collection = new Set();
      var collect = function(match, _wholeGroup, _keyGroup, valueGroup) {
        valueGroup.split(/\s*,+\s*/).forEach(function (value) {
          if (value) {
            collection.add(value);
          }
        });
      };
      message.replace(trailerRegexp, collect);
      if (collection.size > 0) {
        return token + ': ' + Array.from(collection).join(', ') + '\n';
      }
      return '';
    };
  </script>
</dom-module>


<dom-module id="autosubmit-popup">
  <template>
      <gr-dialog
          id="autosubmitDialog"
          confirm-label="Trigger Autosubmit"
          cancel-label="Approve without Autosubmit"
          on-cancel="_handleCancel"
          on-confirm="_handleConfirm">
        <div class="header" slot="header">
          This change's owner has enabled Auto-Submit
        </div>
        <div class="main" slot="main">
          Click "Trigger Autosubmit" if you would like to send this<br/>
          change to the CQ, or "Approve without Autosubmit" if not.<br/>
          <template is="dom-if" if="[[!_isApprovedByAllOtherReviewers()]]">
            <br/>
            <b>Note:</b> Not all reviewers have approved this change!
          </template>
          <template is="dom-if" if="[[unresolvedCommentsOrDrafts]]">
            <br/>
            <b>Note:</b> This change has unresolved comments and/or drafts!
          </template>
        </div>
      </gr-dialog>
  </template>
  <script>
    Polymer({
      is: 'autosubmit-popup',
      properties: {
        unresolvedCommentsOrDrafts: Boolean,
      },
      ready() {
        this._setUnresolvedCommentsOrDrafts();
      },
      _handleConfirm() {
        this._setApprovalLabels(true);
        AUTOSUBMIT_POPUP.close();
      },
      _handleCancel() {
        this._setApprovalLabels(false);
        AUTOSUBMIT_POPUP.close();
      },
      _setApprovalLabels(sendToCQ) {
        setApprovalLabels(sendToCQ).catch(function(err) {
          // Re-enable the quick approve button if there was an error.
          PLUGIN.changeActions().setEnabled(CUSTOM_QUICK_APPROVE_KEY, true);
        }.bind(this));
      },
      _isApprovedByAllOtherReviewers() {
        return _APPROVED_BY_ALL_OTHER_REVIEWERS;
      },
      _setUnresolvedCommentsOrDrafts() {
        getChangeObj().then(function(change) {
          if (change.unresolved_comment_count !== 0) {
            this.unresolvedCommentsOrDrafts = true;
            return;
          }
          getChangeDrafts().then(function(drafts) {
            this.unresolvedCommentsOrDrafts = Object.keys(drafts).length !== 0;
          }.bind(this));
        }.bind(this));
      },
    });
  </script>
</dom-module>


<dom-module id="autosubmit">
  <script>
    /**
     * There are two main flows that need to handle the AS+1 vote:
     * 1. CR+1 in reply dialog should automatically set CQ+2 label without
     *    submitting. An info msg should be displayed to the user in the dialog.
     * 2. CR+1 button on the main page should display a popup asking if CQ+2
     *    should be set since AS+1 is set.
     *
     * This function adds both behaviors. See crbug.com/631551 for more context.
     */
    const installAutoSubmit = function(change) {
      if (!change || !change.permitted_labels) {
        // Could happen if the user is not logged in.
        return;
      }
      if (change.status === STATUS_SUBMITTED) {
        // Do not need autosubmit behavior for already submitted changes.
        return;
      }

      // Save the change's CR and CQ label max values for easy access from
      // different functions.
      _REVIEW_LABEL_MAX_VALUE = getLabelMaxValue(change, REVIEW_LABEL)
      _CQ_LABEL_MAX_VALUE = getLabelMaxValue(change, CQ_LABEL)

      if (_REVIEW_LABEL_MAX_VALUE === 0 || _CQ_LABEL_MAX_VALUE === 0 ||
          !checkLabelAndMaxValue(change, AUTOSUBMIT_LABEL,
                                 AS_LABEL_MAX_VALUE)) {
        // Exit early if project does not have the expected labels with expected
        // max values.
        return;
      }

      if (!isLabelVotePermitted(change, CQ_LABEL, '+' + _CQ_LABEL_MAX_VALUE) ||
          !isLabelVotePermitted(change, REVIEW_LABEL,
                                '+' + _REVIEW_LABEL_MAX_VALUE)) {
        // Exit early if user does not have necessary permissions to CR+1
        // and CQ+2.
        return;
      }

      // Check to see if we are still waiting for any other reviewers to
      // approve.
      checkIfApprovedByAllOtherReviewers(change);

      // Watch for any label value changes to see if CQ+2 should be
      // automatically added.
      const replyApi = PLUGIN.changeReply();
      replyApi.addLabelValuesChangedCallback(
          labelValuesCallback(replyApi, change))

      // Replace the CR+1 button with a custom handler on the main page.
      replaceQuickApproveButton(change, replyApi);
    };

    /**
     * Checks to see if any reviewer, other than the current user and the
     * change owner, has not approved the change yet. Updates the
     * _APPROVED_BY_ALL_OTHER_REVIEWERS global var with the result.
     */
    const checkIfApprovedByAllOtherReviewers = function(change) {
      if (change.reviewers && change.reviewers.REVIEWER) {
        // Gather account_emails of all approvers.
        const approver_emails = [];
        for (let i=0; i<change.labels[REVIEW_LABEL].all.length; i++) {
          if (change.labels[REVIEW_LABEL].all[i].value === 1) {
            approver_emails.push(change.labels[REVIEW_LABEL].all[i].email);
          }
        }
        // Get the account_email of the current user and use that to determine
        // if any other reviewer has not approved the change yet.
        PLUGIN.restApi().get('/accounts/self/detail').then(function(resp) {
          let approvedByAllOtherReviewers = true;
          const current_user_email = resp.email;
          // Check to see if any reviewer, other than the current user and the
          // change owner, has not approved the change yet.
          for (let i=0; i<change.reviewers.REVIEWER.length; i++) {
            const reviewer_email = change.reviewers.REVIEWER[i].email;
            if (reviewer_email != current_user_email &&
                reviewer_email != change.owner.email &&
                !approver_emails.includes(reviewer_email)) {
              approvedByAllOtherReviewers = false;
              break;
            }
          }
          _APPROVED_BY_ALL_OTHER_REVIEWERS = approvedByAllOtherReviewers;
        }.bind(this)).catch(function(err) {
          let changeActions = PLUGIN.changeActions();
          changeActions._el.dispatchEvent(new CustomEvent('show-alert',
              {detail: {message: err}, bubbles: true}));
          throw err;
        });
      }
    };

    /**
     * This is the callback used when label values change. Labels can change
     * from either the reply dialog box or by 'x'ing labels on the main page.
     * There is no page reload when labels change.
     *
     * Algorithm used by the callback:
     *
     *   ownerDeselectedAutoSubmit = false
     *
     *   If label name == Code-Review:
     *     Re-evaluate the quick approve button
     *     If CR+1 and AS+1 and not ownerDeselectedAutoSubmit:
     *       Set CQ+2
     *       Inform user that CQ+2 was automatically set
     *   If label name == Auto-Submit:
     *     Set ownerDeselectedAutoSubmit value
     *     If CR+1 and not ownerDeselectedAutoSubmit:
     *       Set CQ+2
     *       Inform user that CQ+2 was automatically set
     */
    const labelValuesCallback = function(replyApi, change) {
      let ownerDeselectedAutoSubmit = false;
      return ({name, value}) => {
        const reviewApproved = replyApi.getLabelValue(REVIEW_LABEL) ===
                                   '+' + _REVIEW_LABEL_MAX_VALUE;
        const autoSubmitApproved = isAutoSubmitApproved(change, replyApi);
        replyApi.showMessage('');

        if (name === REVIEW_LABEL) {
          // Always re-evaluate the quick approve button when Code-Review label
          // changes. Get the latest change object from the server to be sure we
          // are making the right decisions when displaying the quick approve
          // button (see crbug.com/820117).
          getChangeObj().then(function(refreshedChangeObj) {;
            replaceQuickApproveButton(refreshedChangeObj, replyApi);
            // If CR+1 and AS+1 then set CQ+2 if there are no unresolved
            // comments and/or drafts.
            if (value === '+' + _REVIEW_LABEL_MAX_VALUE && autoSubmitApproved &&
                !ownerDeselectedAutoSubmit) {
              const unresolved_msg = 'This change has unresolved comments ' +
                                     'and/or drafts. Not triggering ' +
                                     'AutoSubmit.';
              if (refreshedChangeObj.unresolved_comment_count !== 0) {
                replyApi.showMessage(unresolved_msg);
              } else {
                getChangeDrafts().then(function(drafts) {
                  if (Object.keys(drafts).length === 0) {
                    replyApi.setLabelValue(CQ_LABEL, '+' + _CQ_LABEL_MAX_VALUE);
                    replyApi.showMessage(getSendToCQReplyDialogMsg());
                  } else {
                    replyApi.showMessage(unresolved_msg);
                  }
                });
              }
            }
          });
        } else if (name === AUTOSUBMIT_LABEL) {
          // The change owner has changed the vote of the Auto-Submit label.
          ownerDeselectedAutoSubmit = (value !== '+' + AS_LABEL_MAX_VALUE);
          if (!ownerDeselectedAutoSubmit && reviewApproved) {
            // If AS+1 and CR+1 then set CQ+2.
            replyApi.setLabelValue(CQ_LABEL, '+' + _CQ_LABEL_MAX_VALUE);
            replyApi.showMessage(getSendToCQReplyDialogMsg());
          }
        }
      };
    };

    /**
     * Returns the autosubmit msg that should be displayed in the reply dialog.
     */
    const getSendToCQReplyDialogMsg = function() {
      let sendToCQMsg = 'This change\'s owner has enabled Auto-Submit. ' +
                        'Your approval will also set CQ+' +
                        _CQ_LABEL_MAX_VALUE +
                        '. Unselect that if you don\'t want to trigger it.'
      if (!_APPROVED_BY_ALL_OTHER_REVIEWERS) {
        sendToCQMsg += '\nNote: Not all reviewers have approved this change!'
      }
      return sendToCQMsg;
    };

    /**
     * Looks at both the replyApi and the change object to determine if
     * AS+1 is set. This checks the replyApi for the case where the owner sets
     * their own AS+1 and CR+1 at the same time. In that case we want to also
     * go ahead and set CQ+1.
     */
    const isAutoSubmitApproved = function(change, replyApi) {
      return (replyApi.getLabelValue(AUTOSUBMIT_LABEL) ===
                  '+' + AS_LABEL_MAX_VALUE ||
              getChangeLabel(change, AUTOSUBMIT_LABEL).approved)
    };

    /**
     * This function replaces the quick approve button with a new button with
     * a custom handler that prompts if AS+1 is set.
     */
    const replaceQuickApproveButton = function(change, replyApi) {
      let changeActions = PLUGIN.changeActions();

      // Make sure the old quick approve button is hidden.
      changeActions.hideQuickApproveAction();

      PLUGIN.restApi().get('/accounts/self/detail').then(function(resp) {
        // See if the current user has approved the change.
        let approved_by_current_user = false;
        for (let i=0; i<change.labels[REVIEW_LABEL].all.length; i++) {
          if (change.labels[REVIEW_LABEL].all[i].value === 1) {
            if (resp._account_id ==
                change.labels[REVIEW_LABEL].all[i]._account_id) {
              approved_by_current_user = true;
              break;
            }
          }
        }

        if (getChangeLabel(change, REVIEW_LABEL).approved &&
            approved_by_current_user) {
          if (CUSTOM_QUICK_APPROVE_KEY !== null) {
            // The custom button is visible but should be now removed because
            // the user set CR+1.
            changeActions.remove(CUSTOM_QUICK_APPROVE_KEY);
            changeActions.removeTapListener(CUSTOM_QUICK_APPROVE_KEY);
            CUSTOM_QUICK_APPROVE_KEY =  null;
          }
          // Do not create a new button because this user already set CR+1.
          return;
        } else if (CUSTOM_QUICK_APPROVE_KEY !== null) {
          // There is already a button no need to create a new one.
          return;
        }

        // Create the custom quick approve button.
        const key = changeActions.add(changeActions.ActionType.CHANGE, 'Code-Review+1');
        changeActions.setEnabled(key, true);
        changeActions.addTapListener(
            key, quickApproveHandler(changeActions, replyApi, change, key));
        changeActions.setActionPriority(
            changeActions.ActionType.CHANGE, key, -3);
        CUSTOM_QUICK_APPROVE_KEY = key;
      }.bind(this)).catch(function(err) {
        let changeActions = PLUGIN.changeActions();
        changeActions._el.dispatchEvent(new CustomEvent('show-alert',
            {detail: {message: err}, bubbles: true}));
        throw err;
      });
    };

    const quickApproveHandler = function(changeActions, replyApi, change, key) {
      return () => {
        // Disable the auto approve button.
        changeActions.setEnabled(key, false);
        if (!isAutoSubmitApproved(change, replyApi) ||
            getChangeLabel(change, CQ_LABEL).approved) {
          // Do not automatically set CQ+2 if AS+1 is not set or if CQ+2
          // is already set.
          setApprovalLabels(false).catch(function(err) {
            // Re-enable the quick approve button if there was an error.
            changeActions.setEnabled(key, true);
          }.bind(this));
        } else {
          if (AUTOSUBMIT_POPUP) {
            AUTOSUBMIT_POPUP.open();
          } else {
            PLUGIN.popup('autosubmit-popup').then(function(pluginModule) {
              AUTOSUBMIT_POPUP = pluginModule;
            });
          }
        }
      };
    };
  </script>
</dom-module>


<dom-module id="lgtm-catcher">
  <script>
    /**
     * Watches for the reviewer to type "LGTM" (not case sensitive) at the
     * beginning of their review message, and automatically sets the
     * Code-Review label to +1 to save the reviewer a click. Doesn't change
     * the value if the user has manually manipulated it already, or if the
     * string "LGTM" appears anywhere else.
     */
    const installLgtmWatcher = function() {
      const replyApi = PLUGIN.changeReply();
      let autoAdded = false;
      replyApi.addReplyTextChangedCallback(text => {
        const labelValue = replyApi.getLabelValue(REVIEW_LABEL);
        if (!labelValue) {
          return;
        }
        if (labelValue === ' 0' && autoAdded === false &&
            text.trim().toLowerCase().indexOf('lgtm') === 0) {
          autoAdded = true;
          replyApi.setLabelValue(REVIEW_LABEL, '+1');
        } else if (labelValue === '+1' && autoAdded === true &&
            text.trim().toLowerCase().indexOf('lgtm') !== 0) {
          autoAdded = false;
          replyApi.setLabelValue(REVIEW_LABEL, ' 0');
        }
      });
    };
  </script>
</dom-module>


<dom-module id="reland-button">
  <script>
    let _CUSTOM_RELAND_KEY = null;

    function maybeInstallReland(change) {
      if (change.status !== STATUS_SUBMITTED) { return; }

      let changeActions = PLUGIN.changeActions();

      if (_CUSTOM_RELAND_KEY !== null) {
        changeActions.remove(_CUSTOM_RELAND_KEY);
      }

      // Show neither the Revert nor Reland actions to non-committer drive-bys.
      PLUGIN.restApi().get('/accounts/self/detail').then(currentUser => {
        if (currentUser.email !== change.owner.email &&
            !isLabelVotePermitted(change, REVIEW_LABEL,
                                  '+' + REVIEW_LABEL_MAX_VALUE)) {
          changeActions.setActionHidden(changeActions.ActionType.CHANGE,
                                        changeActions.ChangeActions.REVERT,
                                        true);
        } else {
          installRelandButton(change, changeActions);
        }
      });
    }

    /**
     * Adds a "Reland" button to the page, if appropriate.
     * @param {ChangeInfo} change: the object for the current change
     */
    const installRelandButton = function(change, changeActions) {
      let newKey = changeActions.add(changeActions.ActionType.CHANGE, 'Reland');
      changeActions.setEnabled(newKey, true);
      let handler = function() {
        changeActions.setEnabled(newKey, false);
        changeActions.setLabel(newKey, 'Reopening...');
        let orig = (
            change.revisions[change.current_revision].commit.message.trim());
        let subject = 'Reland "' + change.subject + '"\n\n';
        let disclaimer = (
            'This is a reland of ' + change.current_revision + '\n\n' +
            'Original change\'s description:\n');
        let quote = orig.replace(/^/gm, '> ');
        let message = subject + disclaimer + quote;
        let bugFooter = getTrailer(orig, 'Bug');
        let cqFooter = getTrailer(orig, 'Cq-Include-Trybots');
        if (bugFooter || cqFooter) {
          message += '\n\n' + bugFooter + cqFooter;
        }
        let url = (
            '/changes/' + change._number + '/revisions/' +
            change.revisions[change.current_revision]._number +
            '/cherrypick');
        let body = {
          message: message.trim(),
          destination: change.branch,
          keep_reviewers: true,
        };
        return PLUGIN.restApi().post(url, body).then(function(response) {
          window.location.pathname = '/c/' + response._number;
        }).catch(function(err) {
          changeActions.setLabel(newKey, 'Can\'t reland');
          changeActions.setEnabled(newKey, false);
          changeActions._el.dispatchEvent(new CustomEvent('show-alert',
              {detail: {message: 'Cannot reland: ' + err}, bubbles: true}));
          throw err;
        });
      };
      changeActions.addTapListener(newKey, handler);
      _CUSTOM_RELAND_KEY = newKey;
    };
  </script>
</dom-module>


<dom-module id="revert-munger">
  <script>
    const _CQ_CHECKBOX_ID = 'cq-checkbox';

    /**
     * Called when the user clicks the "Revert" button to pull up the dialog.
     * @param {ChangeInfo} change: the object for the current change
     * @param {string} revertMsg: the default message Gerrit would use
     * @param {string} originalMsg: the commit message of the original change
     * @returns {string} used to populate the Revert dialog box
     */
    const interceptRevertMessage = function(change, revertMsg, originalMsg) {
      if (!change.labels[CQ_LABEL]) { return revertMsg; }

      // Add CQ checkbox if it does not already exist.
      if (document.getElementById(_CQ_CHECKBOX_ID) == null) {
        let newSpan = document.createElement('span');
        newSpan.classList.add(Gerrit.css('margin: 8px'));
        newSpan.textContent = 'Automatically send revert change to CQ:';

        let cqCheck = document.createElement('input');
        cqCheck.type = 'checkbox';
        cqCheck.id = _CQ_CHECKBOX_ID;
        cqCheck.checked = true;
        cqCheck.classList.add(Gerrit.css('margin-left: 8px'));
        newSpan.appendChild(cqCheck);

        let footer = document.querySelector('#confirmRevertDialog footer');
        footer.parentNode.insertBefore(newSpan, footer);
      }

      // Add email-style quoting ('> ') in front of the original commit text.
      let originalCommitText = originalMsg.trim().replace(/^/gm, '> ');

      // Start constructing the revert change description.

      // Show reverts-of-reverts as relands instead.
      revertMsg = revertMsg.replace(
          /^Revert "Revert "(.*)""/, 'Reland "$1"');

      let newDescription =
          revertMsg + '\n' +
          'Original change\'s description:\n' + originalCommitText + '\n\n';

      // Construct new Bug: trailer.
      let bugLine = getTrailer(originalMsg, 'Bug');
      bugLine += getTrailer(originalMsg, 'Issue');

      // CrOS projects need only the bug line carried over.
      if (change.project.indexOf('chromiumos/') === 0 ||
          change.project.indexOf('chromeos/') === 0) {
        newDescription += bugLine;
        return newDescription.trim();
      }

      // Construct new TBR tag.
      let reviewers = [];
      if (change.reviewers.REVIEWER) {
        reviewers = change.reviewers.REVIEWER.map(function(reviewer) {
          return reviewer.email;
        });
      }
      reviewers = reviewers.filter(function(email) {
        // Do not add Commit bots to TBR. See crbug.com/642739
        return email && !email.endsWith('commit-bot@chromium.org');
      });
      reviewers.push(change.owner.email);
      reviewers = reviewers.filter(function(item, pos, self) {
        return self.indexOf(item) === pos;
      });
      let tbrLine = 'TBR=' + reviewers.join(',') + '\n\n';
      newDescription += tbrLine;

      // Carry over original trybots trailer.
      let includeLine = getTrailer(originalMsg, 'Cq-Include-Trybots');

      // Construct new CQ control trailers, but only include them if the
      // reverted change is recent enough.
      let cqSkip = 'No-Presubmit: true\nNo-Tree-Checks: true\nNo-Try: true\n';
      let submittedDate = new Date(change.submitted + ' UTC');
      let diffSeconds = (Date.now() - submittedDate) / 1000;
      if (diffSeconds > 24 * 60 * 60) {
        alert('Note: The CL will not be automatically sent to the CQ and ' +
              'the CQ checks will not be skipped because this CL landed ' +
              'more than 1 day ago.');
        document.getElementById(_CQ_CHECKBOX_ID).checked = false;
        newDescription += '# Not skipping CQ checks because original CL ' +
                          'landed > 1 day ago.\n\n';
      } else {
        newDescription += cqSkip;
      }

      // Add previously-constructed trailers.
      newDescription += bugLine;
      newDescription += includeLine;

      return newDescription.trim();
    };

    /**
     * Called when the Revert action has been completed.
     * @param {ChangeInfo} change: the object representing the new revert
     * @returns {LabelInfo} the labels to set on the new revert
     */
    const approveAndSubmitRevert = function(change) {
      let labels = {};
      // Auto-approve reverts.
      labels[REVIEW_LABEL] = REVIEW_LABEL_MAX_VALUE;
      // Immediately send to CQ only if _CQ_CHECKBOX_ID is checked.
      if (document.getElementById(_CQ_CHECKBOX_ID).checked) {
        labels[CQ_LABEL] = CQ_LABEL_MAX_VALUE;
      }
      return labels;
    };
  </script>
</dom-module>


<dom-module id="tbr-warner">
  <script>
    const _TBR_REGEX = /^\s*(TBR=|Tbr:).*$/mg;

    /**
     * Warns the user that just adding TBR= to a commit message isn't enough.
     * @param {ChangeInfo} change: the object for the current change
     * @param {string} message: the newly-set commit message
     */
    const warnAboutTbr = function(change, message) {
      let match = _TBR_REGEX.exec(message);
      if (match && change.labels[REVIEW_LABEL] &&
          change.labels[REVIEW_LABEL].approved == null) {
        alert('You have added a TBR line. You must also approve ' +
              'this change for it to be submittable.');
      }
    };
  </script>
</dom-module>


<dom-module id="install">
  <script>
    // Install all of the pieces of functionality defined above.
    // We do just one Gerrit.install because the plugin API expects
    // one install per plugin; if you have multiple installs in a
    // single plugin, the first showchange event might be fired before
    // they're all installed.
    Gerrit.install(plugin => {
      PLUGIN = plugin;
      PLUGIN.on('showchange', installLgtmWatcher);
      PLUGIN.on('showchange', installAutoSubmit);
      PLUGIN.on('showchange', maybeInstallReland);
      PLUGIN.on('commitmsgedit', warnAboutTbr);
      PLUGIN.on('revert', interceptRevertMessage);
      PLUGIN.on('postrevert', approveAndSubmitRevert);
    });
  </script>
</dom-module>