Google Chrome扩展:如何查看用户是否已经登录到Chrome浏览器？

{
  "manifest_version": 2,
  "name": "My Extension",
  "version": "1.0",
  "permissions": [
    "identity"
  ],
  "background": {
    "scripts": ["background.js"],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html"
  }
}

chrome.identity.getAuthToken({ interactive: true }, function(token) {
  if (chrome.runtime.lastError) {
    console.error(chrome.runtime.lastError);
    return;
  }
  console.log("User is logged in with access token: " + token);
});

chrome.identity.getProfileUserInfo(function(userInfo) {
  console.log("User is logged in with email: " + userInfo.email);
});