Passing messages through Promises - google-chrome-extension

Question

I'm trying to make an extension where :
background creates a new blank tab in the browser
then update the new tab with an url
then open a message port to the new tab
then pass a message to content script to retrieve element on the new tab's page
then content script respond to background with the title
I'm trying to do that with Promises, because after above example, I want to make it with an array of urls, so with a for loop. So I need to do it synchronously, one url after one url.
Here's my code :
background.js
function createNewTab() {
return new Promise(function (resolve, reject) {
var newTabId = 0;
chrome.tabs.create({
url: "about:newtab"
}, function(newTab) {
resolve(newTab);
});
});
}
function updateTab(newTab) {
console.log("updateTab try with tab " + newTab.id);
return new Promise(function (resolve, reject) {
chrome.tabs.update(newTab.id, {
url: "https://forum.openstreetmap.fr/viewtopic.php?f=3&t=6811&start=0"
}, function (tab) {
if (tab.url == "https://forum.openstreetmap.fr/viewtopic.php?f=3&t=6811&start=0")
resolve(["updated", tab])
else
reject(["failed", null])
});
});
}
function connectTab(newTab) {
console.log("connectTab try with tab " + newTab.id);
return new Promise(function (resolve, reject) {
var port = chrome.tabs.connect(newTab.id, {
name: "scrap"
});
resolve(port);
});
}
function passMsgToTab(port) {
return new Promise(function (resolve, reject) {
port.postMessage({
type: "title"
});
resolve("passed");
reject("failed");
});
}
createNewTab()
.then(function(newTab) {
console.log("createNewTab newTab : " + newTab.id);
return updateTab(newTab)
})
.then(function(responseTab) {
var response = responseTab[0];
var newTab = responseTab[1];
console.log("updated ? " + response + " | tab : " + newTab.id);
if (response == "updated")
return connectTab(newTab)
})
.then(function (port) {
console.log("connectTab port : " + port.name);
return passMsgToTab(port)
})
.then(function (response) {
console.log("message passed ? " + response);
})
And content_script.js :
chrome.runtime.onConnect.addListener(function (port) {
console.assert(port.name == "scrap");
port.onMessage.addListener(function (msg) {
console.log("recieved msg : " + msg.type);
if (msg.type == "title") {
var title = $("h3.first a").text();
port.postMessage({
title: title
});
}
});
});
So the first 2 steps (createTab & updateTab) success. But message passing fails. I retrieve the response from connectTab but as I'm not putting resolve in a callback function, I think it doesn't work. I can reach port.name from then() but what can I do with this port ? And Where can I put the resolve ?
I think this is the same problem with port.message.