Add 't to add topic' to change view

Currently, this shortcut only works if no topic is already set. Fixing
that case will require a moderate refactor of gr-editable-label and
gr-change-metadata to depend less on the actual change data and more on
component local state, but this is good enough to unblock 2.16.

Bug: Issue 9778
Change-Id: I85d27179268cde6559b78d9f3d4fd34a881a8ca2
diff --git a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
index 0a685da..d1fdf2f 100644
--- a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
+++ b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
@@ -142,6 +142,7 @@
     UP_TO_CHANGE: 'UP_TO_CHANGE',
     TOGGLE_DIFF_MODE: 'TOGGLE_DIFF_MODE',
     REFRESH_CHANGE: 'REFRESH_CHANGE',
+    EDIT_TOPIC: 'EDIT_TOPIC',
 
     NEXT_LINE: 'NEXT_LINE',
     PREV_LINE: 'PREV_LINE',
@@ -223,6 +224,8 @@
       'Refresh list of changes');
   _describe(Shortcut.TOGGLE_CHANGE_STAR, ShortcutSection.ACTIONS,
       'Star/unstar change');
+  _describe(Shortcut.EDIT_TOPIC, ShortcutSection.ACTIONS,
+      'Add a change topic');
 
   _describe(Shortcut.NEXT_LINE, ShortcutSection.DIFFS, 'Go to next line');
   _describe(Shortcut.PREV_LINE, ShortcutSection.DIFFS, 'Go to previous line');
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 e521576..6509bb1 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
@@ -244,6 +244,7 @@
               is="dom-if"
               if="[[_showAddTopic(change.*, _settingTopic)]]">
             <gr-editable-label
+                class="topicEditableLabel"
                 label-text="Add a topic"
                 value="[[change.topic]]"
                 max-length="1024"
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 8b119d8..8d1546b 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
@@ -343,5 +343,12 @@
     _computeIsMutable(account) {
       return !!Object.keys(account).length;
     },
+
+    editTopic() {
+      if (this._topicReadOnly || this.change.topic) { return; }
+      // Cannot use `this.$.ID` syntax because the element exists inside of a
+      // dom-if.
+      this.$$('.topicEditableLabel').open();
+    },
   });
 })();
diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html
index 17c3d70..af25d91 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html
@@ -587,6 +587,20 @@
       });
     });
 
+    test('editTopic', () => {
+      element.account = {test: true};
+      element.change = {actions: {topic: {enabled: true}}};
+      flushAsynchronousOperations();
+
+      const label = element.$$('.topicEditableLabel');
+      assert.ok(label);
+      sandbox.stub(label, 'open');
+      element.editTopic();
+      flushAsynchronousOperations();
+
+      assert.isTrue(label.open.called);
+    });
+
     suite('plugin endpoints', () => {
       test('endpoint params', done => {
         element.change = {labels: {}};
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
index 24453be..16755d5 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
@@ -291,6 +291,7 @@
         [this.Shortcut.EXPAND_ALL_MESSAGES]: '_handleExpandAllMessages',
         [this.Shortcut.COLLAPSE_ALL_MESSAGES]: '_handleCollapseAllMessages',
         [this.Shortcut.OPEN_DIFF_PREFS]: '_handleOpenDiffPrefsShortcut',
+        [this.Shortcut.EDIT_TOPIC]: '_handleEditTopic',
       };
     },
 
@@ -944,6 +945,14 @@
       this.$.downloadOverlay.open();
     },
 
+    _handleEditTopic(e) {
+      if (this.shouldSuppressKeyboardShortcut(e) ||
+          this.modifierPressed(e)) { return; }
+
+      e.preventDefault();
+      this.$.metadata.editTopic();
+    },
+
     _handleRefreshChange(e) {
       if (this.shouldSuppressKeyboardShortcut(e)) { return; }
       e.preventDefault();
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
index df06e55..8c0727a 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
@@ -54,6 +54,7 @@
     kb.bindShortcut(kb.Shortcut.EXPAND_ALL_MESSAGES, 'x');
     kb.bindShortcut(kb.Shortcut.COLLAPSE_ALL_MESSAGES, 'z');
     kb.bindShortcut(kb.Shortcut.OPEN_DIFF_PREFS, ',');
+    kb.bindShortcut(kb.Shortcut.EDIT_TOPIC, 't');
 
     let element;
     let sandbox;
@@ -109,6 +110,12 @@
     });
 
     suite('keyboard shortcuts', () => {
+      test('t to add topic', () => {
+        const editStub = sandbox.stub(element.$.metadata, 'editTopic');
+        MockInteractions.pressAndReleaseKeyOn(element, 83, null, 't');
+        assert(editStub.called);
+      });
+
       test('S should toggle the CL star', () => {
         const starStub = sandbox.stub(element.$.changeStar, 'toggleStar');
         MockInteractions.pressAndReleaseKeyOn(element, 83, null, 's');
diff --git a/polygerrit-ui/app/elements/gr-app.js b/polygerrit-ui/app/elements/gr-app.js
index 9c465f0..0cf517d 100644
--- a/polygerrit-ui/app/elements/gr-app.js
+++ b/polygerrit-ui/app/elements/gr-app.js
@@ -203,6 +203,8 @@
           this.Shortcut.TOGGLE_CHANGE_STAR, 's');
       this.bindShortcut(
           this.Shortcut.REFRESH_CHANGE_LIST, 'shift+r');
+      this.bindShortcut(
+          this.Shortcut.EDIT_TOPIC, 't');
 
       this.bindShortcut(
           this.Shortcut.OPEN_REPLY_DIALOG, 'a');
diff --git a/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.js b/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.js
index b7d65d3..3514492 100644
--- a/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.js
+++ b/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.js
@@ -99,6 +99,12 @@
       });
     },
 
+    open() {
+      return this._open().then(() => {
+        this.$.input.$.input.focus();
+      });
+    },
+
     _open(...args) {
       this.$.dropdown.open();
       this._inputText = this.value;