How to store bearer tokens when MVC and Web API are in different projects
<p><strong>Situation:</strong>
I have a Web API 2 project which acts as an Authorization server (/token endpoint) and a resource server. I am using the template that comes out of box with ASP.Net Web API minus any MVC reference. 
The Start.Auth is configured as below:</p>

<pre><code>public void ConfigureAuth(IAppBuilder app)
        {
            // Configure the db context and user manager to use a single instance per request
            app.CreatePerOwinContext(ApplicationDbContext.Create);
            app.CreatePerOwinContext&lt;ApplicationUserManager&gt;(ApplicationUserManager.Create);

            // Enable the application to use a cookie to store information for the signed in user
            // and to use a cookie to temporarily store information about a user logging in with a third party login provider
            app.UseCookieAuthentication(new CookieAuthenticationOptions());
            app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

            // Configure the application for OAuth based flow
            PublicClientId = "self";
            OAuthOptions = new OAuthAuthorizationServerOptions
            {
                TokenEndpointPath = new PathString("/Token"),
                Provider = new ApplicationOAuthProvider(PublicClientId),
                AuthorizeEndpointPath = new PathString("/Account/ExternalLogin"),
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(14),
                // In production mode set AllowInsecureHttp = false
                AllowInsecureHttp = true
            };

            // Enable the application to use bearer tokens to authenticate users
            app.UseOAuthBearerTokens(OAuthOptions);

            var facebookAuthenticationOptions = new FacebookAuthenticationOptions()
            {
                AppId = ConfigurationManager.AppSettings["Test_Facebook_AppId"],
                AppSecret = ConfigurationManager.AppSettings["Test_Facebook_AppSecret"],
                //SendAppSecretProof = true,
                Provider = new FacebookAuthenticationProvider
                {
                    OnAuthenticated = (context) =&gt;
                    {
                        context.Identity.AddClaim(new System.Security.Claims.Claim("FacebookAccessToken", context.AccessToken));
                        return Task.FromResult(0);
                    }
                }
            };

            facebookAuthenticationOptions.Scope.Add("email user_about_me user_location");
            app.UseFacebookAuthentication(facebookAuthenticationOptions);

        }
</code></pre>

<p>The MVC 5 Client (different Project) uses the Web API app for authorization and data. Below is the code to retrieve the Bearer token in case of Username/Password store:</p>

<pre><code>[HttpPost]
    [AllowAnonymous]
    [ValidateAntiForgeryToken]
    public async Task&lt;ActionResult&gt; Login(LoginViewModel model, string returnUrl)
    {
        if (!ModelState.IsValid)
        {
            model.ExternalProviders = await GetExternalLogins(returnUrl);
            return View(model);
        }

        var client = Client.GetClient();

        var response = await client.PostAsync("Token", 
            new StringContent(string.Format("grant_type=password&amp;username={0}&amp;password={1}", model.Email, model.Password), Encoding.UTF8));

        if (response.IsSuccessStatusCode)
        {
            return RedirectToLocal(returnUrl);
        }
        return View();
    }
</code></pre>

<p><strong>Problem</strong></p>

<p>I could retrieve the Bearer token and then add it to the Authorization Header for subsequent calls. I think that would be ok in case of an Angular App or a SPA. But I think there should be something in MVC that handles it for me, like automatically store it in a cookie and send the cookie on subsequent requests. I have searched around quite a lot and there are posts which hint towards this (<a href="https://stackoverflow.com/questions/21167648/registering-web-api-2-external-logins-from-multiple-api-clients-with-owin-identi">Registering Web API 2 external logins from multiple API clients with OWIN Identity</a>) but I haven't been able to figure out what to do after I get a token.</p>

<p>Do I need to add something in the MVC app Startup.Auth?</p>

<p>Ideally, I need the functionality which the AccountController in ASP.Net Template (MVC + Web API) gives out of box (Logins, Register, External logins, forget password etc etc...) but with the MVC and Web API in different projects.</p>

<p>Is there a template or a git repo which has this boiler plate code?  </p>

<p>Thanks in advance!</p>

<p><strong>Update</strong>
Incorporating @FrancisDucharme suggestions, below is the code for GrantResourceOwnerCredentials().</p>

<pre><code>public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {
            var userManager = context.OwinContext.GetUserManager&lt;ApplicationUserManager&gt;();

            ApplicationUser user = await userManager.FindAsync(context.UserName, context.Password);

            if (user == null)
            {
                context.SetError("invalid_grant", "The user name or password is incorrect.");
                return;
            }

            ClaimsIdentity oAuthIdentity = await user.GenerateUserIdentityAsync(userManager,
               OAuthDefaults.AuthenticationType);
            ClaimsIdentity cookiesIdentity = await user.GenerateUserIdentityAsync(userManager,
                CookieAuthenticationDefaults.AuthenticationType);

            AuthenticationProperties properties = CreateProperties(user.UserName);
            AuthenticationTicket ticket = new AuthenticationTicket(oAuthIdentity, properties);

            //Add a response cookie...
            context.Response.Cookies.Append("Token", context.Options.AccessTokenFormat.Protect(ticket));


            context.Validated(ticket);
            context.Request.Context.Authentication.SignIn(cookiesIdentity);
        }
</code></pre>

<p>But I can't still seem to get that Cookie or figure out what to do next.</p>

<p><strong>Restating Questions:</strong></p>

<ol>
<li>What would be the correct way to authenticate, authorize and call Web API methods (Auth and Resource server) from an MVC client?</li>
<li>Is there boilerplate code or template for AccountController which does the basic plumbing (Login, register - internal/external, forgot password etc.)? </li>
</ol>