How to stop chrome injecting the same script on each click when using chrome.tabs.executeScript

Question

I'm building my first basic chrome extension that when clicked, it takes the url of the current tab, opens a new page at a different address (always the same url) and sends the copied url to it.

I have this working, but for 1 issue. Every time the user clicks the extension, it injects the script. So if they click the extension a second time for the same tab, it will open 2 tabs new tabs, then 3 tabs on the third click, and so on.

I thought I had solved it using this solution but now what happens is when a user clicks the extension for a given tab, it will only open it once, even after 2, 3, 4 clicks (which is good), but if a user switches to a different tab and clicks the extension, nothing happens.

I can kind of see why this is happening, I guess it's now setting a flag for all tabs so once the script is injected in a tab, regardless of which tab, the flag is set and any future injection attempts are blocked. I'm trying to figure out how to set a flag just for the tab that was clicked, and not for all tabs?

Ultimately, I just want the user to be able to click the extension and it will open 1 tab per click.

This is my code

background.js

// Do this when the browser extension icon is clicked
chrome.browserAction.onClicked.addListener(tab => {
    // inject content.js into activeTab

    if (window.qqq !== true) {
        window.qqq = true;
        chrome.tabs.executeScript(tab.id, {
            file: "content.js"
        });
    }

    // Message the active tab to say the extension button has been clicked
    chrome.tabs.query({ active: true, currentWindow: true }, function(tabs) {
        let activeTab = tabs[0];
        chrome.tabs.sendMessage(activeTab.id, {
            message: "add_url_clicked",
        });
    });
});

// Listen for a URL and when received, open the app and append the requested
// URL using HTTP GET
chrome.runtime.onMessage.addListener(request => {
    if (request.message === "open_links_app_with_new_url") {
        chrome.tabs.create({
            url: request.app + "/?url=" + request.destination
        });
    }
});

content.js

// Listen for a browser click and when received, open a new tab with the url created below
chrome.runtime.onMessage.addListener(request => {
    if (request.message === "add_url_clicked") {
        // Get URL to send to app
        let destination = window.location.href;

        localStorage.setItem('url', destination);
        chrome.runtime.sendMessage({
            message: "open_links_app_with_new_url",
            app: "https://destination_url",
            destination: destination
        });
    }
});

and if it helps, manifest.json

{
    "name": "Links",
    "manifest_version": 2,
    "version": "0.2",
    "description": "etc",
    "browser_action": {
        "default_icon": {
         ....
        }
    },
    "permissions": ["activeTab"],
    "background": {
        "scripts": ["background.js"]
    },
    "icons": {
         ....
    }
}