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diff --git a/polygerrit-ui/app/elements/shared/revision-info/revision-info.html b/polygerrit-ui/app/elements/shared/revision-info/revision-info.html
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+<!--
+@license
+Copyright (C) 2017 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.
+-->
+<link rel="import" href="../../../behaviors/gr-patch-set-behavior/gr-patch-set-behavior.html">
+<script>
+  (function() {
+    'use strict';
+
+    /**
+     * @param {Object} change A change object resulting from a change detail
+     *     call that includes revision information.
+     */
+    function RevisionInfo(change) {
+      this._change = change;
+    }
+
+    /**
+     * Get the largest number of parents of the commit in any revision. For
+     * example, with normal changes this will always return 1. For merge changes
+     * wherein the revisions are merge commits this will return 2 or potentially
+     * more.
+     * @return {Number}
+     */
+    RevisionInfo.prototype.getMaxParents = function() {
+      return Object.values(this._change.revisions)
+          .reduce((acc, rev) => Math.max(rev.commit.parents.length, acc), 0);
+    };
+
+    /**
+     * Get an object that maps revision numbers to the number of parents of the
+     * commit of that revision.
+     * @return {!Object}
+     */
+    RevisionInfo.prototype.getParentCountMap = function() {
+      const result = {};
+      Object.values(this._change.revisions)
+          .forEach(rev => { result[rev._number] = rev.commit.parents.length; });
+      return result;
+    };
+
+    /**
+     * @param {number|string} patchNum
+     * @return {number}
+     */
+    RevisionInfo.prototype.getParentCount = function(patchNum) {
+      return this.getParentCountMap()[patchNum];
+    };
+
+    /**
+     * Get the commit ID of the (0-offset) indexed parent in the given revision
+     * number.
+     * @param {number|string} patchNum
+     * @param {number} parentIndex (0-offset)
+     * @return {string}
+     */
+    RevisionInfo.prototype.getParentId = function(patchNum, parentIndex) {
+      const rev = Object.values(this._change.revisions).find(rev =>
+          Gerrit.PatchSetBehavior.patchNumEquals(rev._number, patchNum));
+      return rev.commit.parents[parentIndex].commit;
+    };
+
+    if (!window.Gerrit) {
+      window.Gerrit = {};
+    }
+    window.Gerrit.RevisionInfo = RevisionInfo;
+  })();
+</script>