func jsSignInGoogleHandler(ctx *app.Context) {
code := ctx.RequireFormValue(oauth2.Code)
redir := "postmessage" // this is the redir value used for G+ JS sign in
d := data(ctx)
googleApp := d.opts.GoogleApp.Clone(ctx)
token, err := googleApp.Exchange(redir, code)
if err != nil {
panic(err)
}
user, err := userFromGoogleToken(ctx, googleApp, token)
if err != nil {
panic(err)
}
ctx.MustSignIn(asGondolaUser(user))
writeJSONEncoded(ctx, user)
}