Google OAuth 2.0 DelegatingHandler

AuthenticationHandler.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Security.Claims;
using System.Security.Principal;
using System.Threading;
using System.Threading.Tasks;
using System.Web;

namespace N3rd.Web.MessageHandlers
{
    public class AuthenticationHandler : DelegatingHandler
    {

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            IEnumerable<string> authorizationHeaders = null;
            if (request.Headers.TryGetValues("Authorization", out authorizationHeaders))
            {
                await ValidateAuthorizationHeaderAsync(authorizationHeaders.First());
            }

            return await base.SendAsync(request, cancellationToken);
        }

        private async Task ValidateAuthorizationHeaderAsync(string authorizationHeader)
        {
            var credentials = authorizationHeader.Split(' ');

            if (credentials.Length >= 2)
            {
                var authScheme = credentials[0];
                var authParam = credentials[1];

                if ("Bearer".Equals(authScheme, StringComparison.InvariantCultureIgnoreCase))
                {
                    await ValidateBearerTokenAsync(authParam);
                }
            }
        }

        private async Task ValidateBearerTokenAsync(string bearerToken)
        {
            var httpClient = new HttpClient();
            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=" + bearerToken);
            var response = await httpClient.SendAsync(request);
            if (response.StatusCode == HttpStatusCode.OK)
            {
                dynamic json = await response.Content.ReadAsAsync<dynamic>();
                SetClaimsPrincipal(json);
            }
        }

        private void SetClaimsPrincipal(dynamic json)
        {
            var usernameClaim = new Claim(ClaimTypes.Name, (string) json.email);
            var identity = new ClaimsIdentity(new[] { usernameClaim }, "Google");
            var principal = new ClaimsPrincipal(identity);

            SetPrincipal(principal);
        }

        private void SetPrincipal(IPrincipal principal)
        {
            Thread.CurrentPrincipal = principal;
            if (HttpContext.Current != null)
            {
                HttpContext.Current.User = principal;
            }
        }

    }
}