Пример кода изменения User-Agent для Android.
var MOBILE_CHROME_USER_AGENT = 'Mozilla/5.0 (Linux; U; Android-4.0.3; en-us; Galaxy Nexus Build/IML74K) AppleWebKit/535.7 (KHTML, like Gecko) CrMo/16.0.912.75 Mobile Safari/535.7';
chrome.webRequest.onBeforeSendHeaders.addListener(
function(details) {
for (var i = 0; i < details.requestHeaders.length; ++i) {
if (details.requestHeaders[i].name === 'User-Agent') {
details.requestHeaders[i].value = MOBILE_CHROME_USER_AGENT;
break;
}
}
return {requestHeaders: details.requestHeaders};
}, {urls: ['<all_urls>']}, ['blocking', 'requestHeaders']);