title: Google+ Sign-In button fails with Uncaught SecurityError
body: <p>I am getting this error on my Chrome console:</p>
  
  <pre><code>Uncaught SecurityError: Blocked a frame with origin https://&lt;my-appspot-id&gt;.appspot.com" from accessing a frame with origin "https://accounts.google.com". Protocols, domains, and ports must match. 
  </code></pre>
  
  <p>The symptom, is that when I click the Google+ sign-in button, A Google Auth window/popup/frame appears and nothing happens.</p>
  
  <p>As you can see, I am browsing my site using <strong>https</strong> already. My web application OAuth configuration is also set to use https (javascript origins field) .</p>
  
  <p>Local testing works fine. </p>
  
  <p>What is wrong with my setup?</p>