Use base url for commentlink

Bug: Issue 11344
Change-Id: I68aa21f81e88441f01b9386fdbf77fbb93810ec3
(cherry picked from commit 8e7bde0da1)

polygerrit-ui/app/elements/shared/gr-linked-text/gr-linked-text.html

@@ -15,7 +15,9 @@ limitations under the License.
 -->
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../../behaviors/base-url-behavior/base-url-behavior.html">
 <link rel="import" href="../../../styles/shared-styles.html">
+<link rel="import" href="../../core/gr-navigation/gr-navigation.html">
 
 <script src="ba-linkify.js"></script>
 <script src="link-text-parser.js"></script>

polygerrit-ui/app/elements/shared/gr-linked-text/gr-linked-text_test.html

@@ -122,6 +122,24 @@ limitations under the License.
       assert.equal(linkEl.textContent, changeID);
     });
 
+    test('Change-Id pattern was parsed and linked with base url', function() {
+      window.CANONICAL_PATH = '/r';
+
+      // "Change-Id:" pattern.
+      const changeID = 'I11d6a37f5e9b5df0486f6c922d8836dfa780e03e';
+      const prefix = 'Change-Id: ';
+      element.content = prefix + changeID;
+
+      const textNode = element.$.output.childNodes[0];
+      const linkEl = element.$.output.childNodes[1];
+      assert.equal(textNode.textContent, prefix);
+      const url = '/r/q/' + changeID;
+      assert.equal(linkEl.target, '_blank');
+      // Since url is a path, the host is added automatically.
+      assert.isTrue(linkEl.href.endsWith(url));
+      assert.equal(linkEl.textContent, changeID);
+    });
+
     test('Multiple matches', function() {
       element.content = 'Issue 3650\nIssue 3450';
       var linkEl1 = element.$.output.childNodes[0];

polygerrit-ui/app/elements/shared/gr-linked-text/link-text-parser.js

@@ -96,6 +96,10 @@ GrLinkTextParser.prototype.addLink =
     return;
   }
   if (!this.hasOverlap(position, length, outputArray)) {
+    const baseUrl = Gerrit.BaseUrlBehavior.getBaseUrl();
+    if (!!baseUrl && href.startsWith('/') && !href.startsWith(baseUrl)) {
+      href = baseUrl + href;
+    }
     this.addItem(text, href, null, position, length, outputArray);
   }
 };