Show indicator when change parent is out of date

If the parent of the commit is no longer the tip of the target branch,
it becomes possible to rebase the change on that branch. With this
change, the change metadata section shows an out of date indicator next
to the abbreviated parent hash.

The indicator is only shown on non-merge changes for authenticated
users.

Bug: Issue 4655
Change-Id: I6cb4d280352bb37214b853760c6723597690010a

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html

@@ -28,6 +28,7 @@ limitations under the License.
 <link rel="import" href="../../shared/gr-editable-label/gr-editable-label.html">
 <link rel="import" href="../../shared/gr-label/gr-label.html">
 <link rel="import" href="../../shared/gr-linked-chip/gr-linked-chip.html">
+<link rel="import" href="../../shared/gr-tooltip-content/gr-tooltip-content.html">
 <link rel="import" href="../../shared/gr-rest-api-interface/gr-rest-api-interface.html">
 <link rel="import" href="../gr-commit-info/gr-commit-info.html">
 <link rel="import" href="../gr-reviewer-list/gr-reviewer-list.html">
@@ -135,6 +136,13 @@ limitations under the License.
       .parentList gr-commit-info {
         display: inline-block;
       }
+      #parentNotCurrentMessage {
+        display: none;
+      }
+      .parentList.notCurrent.nonMerge #parentNotCurrentMessage {
+        --arrow-color: red;
+        display: inline-block;
+      }
       @media screen and (max-width: 50em), screen and (min-width: 75em) {
         :host {
           display: table;
@@ -236,13 +244,18 @@ limitations under the License.
       <section>
         <span class="title">[[_computeParentsLabel(_currentParents)]]</span>
         <span class="value">
-          <ol class$="[[_computeParentListClass(_currentParents)]]">
+          <ol class$="[[_computeParentListClass(_currentParents, parentIsCurrent)]]">
             <template is="dom-repeat" items="[[_currentParents]]" as="parent">
               <li>
                 <gr-commit-info
                     change="[[change]]"
                     commit-info="[[parent]]"
                     server-config="[[serverConfig]]"></gr-commit-info>
+                <gr-tooltip-content
+                    id="parentNotCurrentMessage"
+                    has-tooltip
+                    show-icon
+                    title$="[[_notCurrentMessage]]"></gr-tooltip-content>
               </li>
             </template>
           </ol>

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js

@@ -25,6 +25,8 @@
     CHERRY_PICK: 'Cherry Pick',
   };
 
+  const NOT_CURRENT_MESSAGE = 'Not current - rebase possible';
+
   Polymer({
     is: 'gr-change-metadata',
 
@@ -46,6 +48,12 @@
        * @type {{ note_db_enabled: string }}
        */
       serverConfig: Object,
+      parentIsCurrent: Boolean,
+      _notCurrentMessage: {
+        type: String,
+        value: NOT_CURRENT_MESSAGE,
+        readOnly: true,
+      },
       _topicReadOnly: {
         type: Boolean,
         computed: '_computeTopicReadOnly(mutable, change)',
@@ -425,8 +433,12 @@
       return parents.length > 1 ? 'Parents' : 'Parent';
     },
 
-    _computeParentListClass(parents) {
-      return parents.length > 1 ? 'parentList merge' : 'parentList';
+    _computeParentListClass(parents, parentIsCurrent) {
+      return [
+        'parentList',
+        parents.length > 1 ? 'merge' : 'nonMerge',
+        parentIsCurrent ? 'current' : 'notCurrent',
+      ].join(' ');
     },
   });
 })();

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html

@@ -336,6 +336,18 @@ limitations under the License.
           'Parents');
     });
 
+    test('_computeParentListClass', () => {
+      const parent = {commit: 'abc123', subject: 'My parent commit'};
+      assert.equal(element._computeParentListClass([parent], true),
+          'parentList nonMerge current');
+      assert.equal(element._computeParentListClass([parent], false),
+          'parentList nonMerge notCurrent');
+      assert.equal(element._computeParentListClass([parent, parent], false),
+          'parentList merge notCurrent');
+      assert.equal(element._computeParentListClass([parent, parent], true),
+          'parentList merge current');
+    });
+
     test('_showAddTopic', () => {
       assert.isTrue(element._showAddTopic(null, false));
       assert.isTrue(element._showAddTopic({base: {topic: null}}, false));

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html

@@ -370,6 +370,7 @@ limitations under the License.
               server-config="[[_serverConfig]]"
               missing-labels="[[_missingLabels]]"
               mutable="[[_loggedIn]]"
+              parent-is-current="[[!_rebaseOriginallyEnabled]]"
               on-show-reply-dialog="_handleShowReplyDialog">
           </gr-change-metadata>
           <!-- Plugins insert content into following container.

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js

@@ -224,6 +224,7 @@
         value: false,
         observer: '_updateToggleContainerClass',
       },
+      _rebaseOriginallyEnabled: Boolean,
     },
 
     behaviors: [
@@ -937,6 +938,7 @@
       if (revisionActions && revisionActions.rebase) {
         revisionActions.rebase.rebaseOnCurrent =
             !!revisionActions.rebase.enabled;
+        this._rebaseOriginallyEnabled = !!revisionActions.rebase.enabled;
         revisionActions.rebase.enabled = true;
       }
       return revisionActions;

polygerrit-ui/app/elements/shared/gr-tooltip-content/gr-tooltip-content.html

@@ -19,6 +19,11 @@ limitations under the License.
 
 <dom-module id="gr-tooltip-content">
   <template>
+    <style>
+      .arrow {
+        color: var(--arrow-color);
+      }
+    </style>
     <slot></slot><!--
  --><span class="arrow" hidden$="[[!showIcon]]">&#9432;</span>
   </template>