title: Implement google login in existing mvc
body: <p>I have a MVC project without Identity (custom authentication). But then I want to implement Google and Facebook authentication to it.</p>
  
  <p>I created a project apart of this to see how microsoft does that in MVC Identity Authentication. I was able to implement part of it.  Right now I have button that invoke the google authentication page, when I select my email to login it has an error with - <strong>Error: redirect_uri_mismatch</strong> - but I force in URL to match with mine URL, which works.</p>
  
  <p>Google is able to invoke my Action in Account Controller, however and looking to MVC base code that I copied, I'm not able to retrieve information about the user.</p>
  
  <p>This is my method that returns null in loginInfo</p>
  
  <pre><code>    public async Task&lt;ActionResult&gt; LoginWithGoogle(string returnUrl)
      {
          var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
  </code></pre>
  
  <p>THis is the AuthenticationManager</p>
  
  <pre><code>    private IAuthenticationManager AuthenticationManager
      {
          get
          {
              return HttpContext.GetOwinContext().Authentication;
          }
      }
  </code></pre>
  
  <p>How can I get information from google authentication? I'm able to do this by javascript but I would like how to do only with C#.</p>
  
  <p>Thanks in advance.</p>