[FIX] mail: no wait init_messaging before loading webclient

Before this commit, discuss widgets had to wait for the route
`mail/init_messaging`. This behaviour slowed down the loading of the
web client.

This commit solves the issue by rendering discuss widgets even when
`mail/init_messaging` hasn't been resolved. For instance, the
messaging menu displays a spinner until messaging becomes ready.

Task-Id 2072835

closes odoo/odoo#37031

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/addons/mail/static/src/js/services/mail_document_thread_manager.js b/addons/mail/static/src/js/services/mail_document_thread_manager.js
index 6bb66b1b439..652567baf14 100644
--- a/addons/mail/static/src/js/services/mail_document_thread_manager.js
+++ b/addons/mail/static/src/js/services/mail_document_thread_manager.js
@@ -34,7 +34,7 @@ MailManager.include({
                     this.call('local_storage', 'getItem', key);
             }
         }
-        this.isReady().then(this._updateDocumentThreadWindows.bind(this, this._documentThreadWindowStates));
+        this._mailBus.on('messaging_ready', this, this._updateDocumentThreadWindows.bind(this, this._documentThreadWindowStates));
         // listen to localStorage changes to synchronize DocumentThread's
         // windows between tabs
         this.call('local_storage', 'onStorage', this, this._onStorage);
diff --git a/addons/mail/static/src/js/services/mail_manager.js b/addons/mail/static/src/js/services/mail_manager.js
index 3ed4031abeb..950ac8c5cd6 100644
--- a/addons/mail/static/src/js/services/mail_manager.js
+++ b/addons/mail/static/src/js/services/mail_manager.js
@@ -46,6 +46,7 @@ var PREVIEW_MSG_MAX_SIZE = 350;  // optimal for native english speakers
 
 var MailManager =  AbstractService.extend({
     dependencies: ['ajax', 'bus_service', 'local_storage'],
+    _isReady: false,
     _ODOOBOT_ID: ["ODOOBOT", "ODOOBOT"], // authorID for transient messages
 
     /**
@@ -294,7 +295,7 @@ var MailManager =  AbstractService.extend({
      * This is the case when it has fetched the initial state from the server,
      * by means of the route 'mail/init_messaging'
      *
-     * @returns {Promise}
+     * @returns {boolean}
      */
     isReady: function () {
         return this._isReady;
@@ -636,7 +637,7 @@ var MailManager =  AbstractService.extend({
      */
     _fetchMailStateFromServer: function () {
         var self = this;
-        this._isReady = session.is_bound.then(function () {
+        session.is_bound.then(function () {
             var context = _.extend(
                 { isMobile: config.device.isMobile },
                 session.user_context
@@ -648,6 +649,8 @@ var MailManager =  AbstractService.extend({
         }).then(function (result) {
             self._updateInternalStateFromServer(result);
             self.call('bus_service', 'startPolling');
+            self._isReady = true;
+            self._mailBus.trigger('messaging_ready');
         });
     },
     /**