I have the following simple codes (partial):

manifest.json

  "side_panel": {
    "default_path": "sidepanel.html"
  },
  "action": {},
  "permissions": ["sidePanel", "storage", "scripting", "tabCapture", "offscreen"]

background.js

chrome.runtime.onInstalled.addListener(() => {
  chrome.sidePanel.setPanelBehavior({ openPanelOnActionClick: true });
});

chrome.action.onClicked.addListener(async (tab) => {
    // if you add the following code inside the onMessage.addListener 
    // you will get this error: "Unchecked runtime.lastError: The message port closed before a response was received"
    // you should add the offscreen inside the onClicked event
    const existingContexts = await chrome.runtime.getContexts({});
    let recording = false;
    
    console.log("[==] Context");
    console.log(existingContexts);
    console.log("[==] Context");
    
    const offscreenDocument = existingContexts.find(
        (c) => c.contextType === 'OFFSCREEN_DOCUMENT'
    );
    
    console.log("[==] Context offscreenDocument");
    console.log(offscreenDocument);
    console.log("[==] Context offscreenDocument");

    // If an offscreen document is not already open, create one.
    if (!offscreenDocument) {
        console.log("[!!] Create offscreen document");
        // Create an offscreen document.
        await chrome.offscreen.createDocument({
          url: 'offscreen.html',
          reasons: ['USER_MEDIA'],
          justification: 'Recording from chrome.tabCapture API'
        });
    }
});

offscreen.js

chrome.runtime.onMessage.addListener(async (message) => {
    console.log("OFFSCREEN");
    console.log(message);
    console.log("OFFSCREEN");
});

sidepanel.js

document.getElementById('delete-button').addEventListener('click', function() {
    console.log("Send Event Button Remove..");
    chrome.runtime.sendMessage({action: 'RemoveTestButton'}, function(response) {
      console.log(`message from background: ${JSON.stringify(response)}`);
    });
});

The strange thing is that I can debug background.js and sidepanel.js but I cannot see any event on offscreen.js (which should be included by chrome.action.onClicked.addListener and the createDocument). In the chrome extension detail I can see background.js and sidepanel.html but not offscreen.html

I am a bit confused on to why this happens because as soon as I click the extension button the should include the offscreen.html file, but it’s not.

Any idea what I am doing wrong?

Thanks