Associate a custom user agent to a specific Google Chrome page/tab

Question

I'm developing a Google Chrome extension and I'd like to set up a specific user agent to a tab/page, or to a popup (iframe shown as a "bubble popup"), without affecting other pages or tabs.

Is it possible?

Answer 1

The webRequest API can be used to modify the User Agent header.
Note: The Network tab at the Developer tools show the old headers. I've verified that the headers are set correctly, using netcat (nc -l 127.0.0.1 -p 6789).

In the example below, the code activates on all tabs. Adjust the request filter to meet your requirements. Add tabId to limit the functionality to this filter, with the tabId of your tabs (obtainable through various APIs, chrome.tabs in particular).

background.js

chrome.webRequest.onBeforeSendHeaders.addListener(
    function(info) {
        // Replace the User-Agent header
        var headers = info.requestHeaders;
        headers.forEach(function(header, i) {
            if (header.name.toLowerCase() == 'user-agent') { 
                header.value = 'Spoofed UA';
            }
        });  
        return {requestHeaders: headers};
    },
    // Request filter
    {
        // Modify the headers for these pages
        urls: [
            "http://stackoverflow.com/*",
            "http://127.0.0.1:6789/*"
        ],
        // In the main window and frames
        types: ["main_frame", "sub_frame"]
    },
    ["blocking", "requestHeaders"]
);

manifest.json

{
  "name": "WebRequest UA test",
  "version": "1.0",
  "permissions": ["webRequest", "webRequestBlocking", "http://*/*"],
  "background": {
    "scripts": ["background.js"]
  },
  "manifest_version": 2
}

Documentation

• chrome.webRequest.onbeforeSendHeaders event
• The Request filter