Added shorthash with Gitiles link to commit.

Modified gr-change-metadata to use CommitInfo data gathered from
Gerrit API /changes/{change-id}/revisions/{revision-id}/commit?links.

Bug: Issue 3950
Bug: Issue 4032
Change-Id: Ia070ff8bad357995d7933a7bf0ef4fbb4c82dfa9
diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html
index d416e14..5f76a79 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html
@@ -104,6 +104,18 @@
       <span class="value">[[change.branch]]</span>
     </section>
     <section>
+      <span class="title">Commit</span>
+      <span class="value">
+        <template is="dom-if" if="[[_computeShowWebLink(commitInfo)]]">
+          <a target="_blank"
+              href$="[[_computeWebLink(commitInfo)]]">[[_computeShortHash(change)]]</a>
+        </template>
+        <template is="dom-if" if="[[!_computeShowWebLink(commitInfo)]]">
+          [[_computeShortHash(change)]]
+        </template>
+      </span>
+    </section>
+    <section>
       <span class="title">Topic</span>
       <span class="value">[[change.topic]]</span>
     </section>
diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
index 4fa98ca..8e2e000 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
@@ -27,6 +27,7 @@
 
     properties: {
       change: Object,
+      commitInfo: Object,
       mutable: Boolean,
       serverConfig: Object,
     },
@@ -35,6 +36,18 @@
       Gerrit.RESTClientBehavior,
     ],
 
+    _computeShowWebLink: function(commitInfo) {
+      return commitInfo.web_links && commitInfo.web_links.length;
+    },
+
+    _computeWebLink: function(commitInfo) {
+      return '../../' + commitInfo.web_links[0].url;
+    },
+
+    _computeShortHash: function(change) {
+      return change.current_revision.slice(0, 6);
+    },
+
     _computeHideStrategy: function(change) {
       return !this.changeIsOpen(change.status);
     },
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
index 3175517..93ef4cd 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
@@ -248,6 +248,7 @@
         <div class="changeInfo-column changeMetadata">
           <gr-change-metadata
               change="[[_change]]"
+              commit-info="[[_commitInfo]]"
               server-config="[[serverConfig]]"
               mutable="[[_loggedIn]]"></gr-change-metadata>
           <gr-change-actions id="actions"