How to stop Google+ Sign-In Button from popping up the message “Welcome back, you've already connected with this app via Google+ Sign-In as …”

Question

I\'m adding Google+ sign in button to my site using the server-side flow. Here is how I render the sign in button:

Answer 1

First, the message only appears the first time that a user is signing in as recognized by Google for a particular browser session. In other words, the user will only see the message if they have closed their browser windows and have started a new browser session.

You should be authorizing the user any time that you are seeing the authorization result successfully returning and updating the user to an authorized state. As such, the user is getting automatically signed in whenever this message appears.

Because the message that appears is there to inform your users that they have automatically been signed in, you probably should not be suppressing this message unless you are doing it intentionally for a user whose session you are explicitly managing.

However, if you have implemented explicit sign-out and are managing the user's signed-in state, the following code change to the plusone.js synchronous include will suppress the toast message.

Another note, you no longer need to manage the user's state to sign the user out. The new method gapi.auth.signOut will sign the user out. You can see a demo of signout here.

If you are doing an asynchronous include, the following global configuration flags will suppress the message:

window.___gcfg = { isSignedOut: true };

UPDATE:

As pointed out by Chimdi2000 this solution does not work in Chrome. You can add the following CSS to hide the generated iframe:

iframe[src^="https://apis.google.com"] {
  display: none;
}

As his answer is far more complete than mine and addresses additional issues, please check it out.