[IMP] mail: do not wait for init_messaging at webclient startup

The messaging service starts synchronously and exposes a promise
isReady that is resolved when the call to init_messaging is done.
This is good as this call thus doesn't slow down the services
startup and thus the webclient mount.

Unfortunately, the ChatWindowContainer, which is a main component,
i.e. a child of the WebClient, waits for that promise in its
onWillStart. As a consequence, the webclient can't be mounted
until the rpc returns, which can take a while (in odoo.com, this
rpc lasts ~500ms).

The chat windows being "peripherical components", there's no reason
to block the whole application for them. Instead, the webclient
can be mounted, and when they are ready, the chat windows can be
rendered. This is what this commit does.

Back-port of https://github.com/odoo/odoo/pull/139750/

closes odoo/odoo#140056

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/mail/static/src/core/common/chat_window_container.js

@@ -7,15 +7,7 @@ import {
     CHAT_WINDOW_WIDTH,
 } from "@mail/core/common/chat_window_service";
 
-import {
-    Component,
-    onWillStart,
-    useExternalListener,
-    useState,
-    onMounted,
-    useRef,
-    useEffect,
-} from "@odoo/owl";
+import { Component, useExternalListener, useState, onMounted, useRef, useEffect } from "@odoo/owl";
 
 import { browser } from "@web/core/browser/browser";
 import { Dropdown } from "@web/core/dropdown/dropdown";
@@ -48,9 +40,8 @@ export class ChatWindowContainer extends Component {
         this.hiddenMenuRef = useRef("hiddenMenu");
         useEffect(
             () => this.setHiddenMenuOffset(),
-            () => [this.chatWindowService.hidden]
+            () => [this.chatWindowService.hidden, this.store.isMessagingReady]
         );
-        onWillStart(() => this.messaging.isReady);
         onMounted(() => this.setHiddenMenuOffset());
 
         this.onResize();

addons/mail/static/src/core/common/chat_window_container.xml

@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
 
 <t t-name="mail.ChatWindowContainer">
-    <div class="o-mail-ChatWindowContainer" t-if="!store.discuss.isActive or ui.isSmall">
+    <div class="o-mail-ChatWindowContainer" t-if="store.isMessagingReady and (!store.discuss.isActive or ui.isSmall)">
         <div t-if="chatWindowService.hidden.length > 0 and !ui.isSmall" t-ref="hiddenMenu" class="o-mail-ChatWindow-hiddenMenuContainer position-fixed bottom-0">
             <t t-call="mail.ChatWindowHiddenMenu"/>
         </div>