service_worker.js

'use strict';
var connections = {};

chrome.runtime.onConnect.addListener(function (port) {

    var extensionListener = function (message) {
        // The original connection event doesn't include the tab ID of the
        // DevTools page, so we need to send it explicitly.
        if (message.name == 'init') {
            connections[message.tabId] = port;
            return;
        }
    }

    // Listen to messages sent from the DevTools page
    port.onMessage.addListener(extensionListener);

    port.onDisconnect.addListener(function (port) {
        port.onMessage.removeListener(extensionListener);

        var tabs = Object.keys(connections);
        for (var i = 0, len = tabs.length; i < len; i++) {
            if (connections[tabs[i]] == port) {
                delete connections[tabs[i]];
                break;
            }
        }
    });
});

// Receive message from content script and relay to the devTools page for the
// current tab
chrome.runtime.onMessage.addListener(function (request, sender, sendResponse) {
    // Messages from content scripts should have sender.tab set
    if (sender.tab) {
        let tabId = sender.tab.id;
        if (request.payload && request.payload.mojitoDetected) {
            // change extension icon to enable state
            chrome.action.setIcon({
                tabId: tabId,
                path: 'images/logo.png'
            });

            if (request.payload.mojitoVersion) {
                chrome.action.setPopup({
                    tabId: tabId,
                    popup: 'popups/popup.html?mojitoVersion=' + request.payload.mojitoVersion + '&containerName=' + request.payload.containerName + '&pageHostname=' + request.payload.pageHostname
                });
            } else {
                chrome.action.setPopup({
                    tabId: tabId,
                    popup: 'popups/popup.html'
                });
            }

            if ('count' in request.payload) {
                // update count of activated experiments on the page
                chrome.action.setBadgeText({ text: String(request.payload.count), tabId: tabId });
                chrome.action.setBadgeBackgroundColor({ color: '#3498db', tabId: tabId });
            }
        }

        if (tabId in connections) {
            /*if (request.target == 'Panel') {
                connections[tabId].postMessage(request);
            }*/
            connections[tabId].postMessage(request);
        }
    }

    return true;
});