code: function(user) {
    document.getElementById('user-signed-in').style.display = 'block';
    document.getElementById('user-signed-out').style.display = 'none';
    document.getElementById('name').textContent = user.displayName;
    document.getElementById('email').textContent = user.email;
    document.getElementById('phone').textContent = user.phoneNumber;
    if (user.photoURL){
      var photoURL = user.photoURL;
      // Append size to the photo URL for Google hosted images to avoid requesting
      // the image with its original resolution (using more bandwidth than needed)
      // when it is going to be presented in smaller size.
      if ((photoURL.indexOf('googleusercontent.com') != -1) ||
          (photoURL.indexOf('ggpht.com') != -1)) {
        photoURL = photoURL + '?sz=' +
            document.getElementById('photo').clientHeight;
      }
      document.getElementById('photo').src = photoURL;
      document.getElementById('photo').style.display = 'block';
    } else {
      document.getElementById('photo').style.display = 'none';
    }
  }
docs: Displays the UI for a signed in user.
  @param {!firebase.User} user