[FIX] mail: no '#' prefix in DM name

Before this commit, DMs had the prefix '#' in their
displayed name (e.g. '#Demo User').

This commit fixes the issue by putting this prefix
only on non-chat DMs. In particular, mailboxes, DMs
and Livechats no longer show this prefix. This change
is also visible in the breadcrumb of the discuss app.

Task-ID 1911738

addons/mail/static/src/js/discuss.js

@@ -852,7 +852,7 @@ var Discuss = AbstractAction.extend(ControlPanelMixin, {
 
             // Update control panel before focusing the composer, otherwise
             // focus is on the searchview
-            self.set("title", '#' + self._thread.getName());
+            self.set("title", self._thread.getTitle());
             self._updateControlPanel();
             self._updateControlPanelButtons(self._thread);
 

addons/mail/static/src/js/models/threads/channel.js

@@ -221,16 +221,6 @@ var Channel = SearchableThread.extend(ThreadTypingMixin, {
             isMyselfAuthor: this.hasMessages() && this.getLastMessage().isMyselfAuthor(),
         });
     },
-    /**
-     * Returns the title to display in thread window's headers.
-     * For channels, the title is prefixed with "#".
-     *
-     * @override
-     * @returns {string|Object} the name of the thread by default (see getName)
-     */
-    getTitle: function () {
-        return "#" + this._super.apply(this, arguments);
-    },
     /**
      * Get the UUID of the channel.
      * This is a string that uniquely links this channel to a server channel.

addons/mail/static/src/js/models/threads/multi_user_channel.js

@@ -25,6 +25,16 @@ var MultiUserChannel = Channel.extend({
     // Public
     //--------------------------------------------------------------------------
 
+    /**
+     * Returns the title to display in thread window's headers.
+     * For channels, the title is prefixed with "#".
+     *
+     * @override
+     * @returns {string|Object} the name of the thread by default (see getName)
+     */
+    getTitle: function () {
+        return "#" + this._super.apply(this, arguments);
+    },
     /**
      * States whether this thread has the mass mailing setting active or not.
      * This is a server-side setting, that determine the type of composer that

addons/mail/static/tests/thread_window/blank_thread_window_tests.js

@@ -229,7 +229,7 @@ QUnit.test('open new DM chat from blank thread window', function (assert) {
     selectDef.then(function () {
         assert.strictEqual($('.o_thread_window').length, 1,
             "should be a single window");
-        assert.strictEqual($('.o_thread_window_title').text().trim(), "#DemoUser1",
+        assert.strictEqual($('.o_thread_window_title').text().trim(), "DemoUser1",
             "should have thread window of the DM chat with 'DemoUser1'");
         assert.strictEqual($('.o_composer_text_field').length, 1,
             "should have a composer in the DM chat window");
@@ -285,7 +285,7 @@ QUnit.test('open already detached DM chat from blank thread window', function (a
 
     assert.strictEqual($('.o_thread_window').length, 1,
         "should be a single window");
-    assert.strictEqual($('.o_thread_window_title').text().trim(), "#DemoUser1",
+    assert.strictEqual($('.o_thread_window_title').text().trim(), "DemoUser1",
         "should have thread window of the DM chat with 'DemoUser1'");
     assert.strictEqual($('.o_composer_text_field').length, 1,
         "should have a composer in the DM chat window");
@@ -304,7 +304,7 @@ QUnit.test('open already detached DM chat from blank thread window', function (a
     selectDef.then(function () {
         assert.strictEqual($('.o_thread_window').length, 1,
             "should now have a single thread window open");
-        assert.strictEqual($('.o_thread_window_title').text().trim(), "#DemoUser1",
+        assert.strictEqual($('.o_thread_window_title').text().trim(), "DemoUser1",
             "the remaining thread window should be the DM chat with 'DemoUser1'");
 
         self.unpatchAutocomplete();