Cleaning up the solution. Separating Shared.WinRT, Services and Synchronization. Removing synchronization from app. Reducing bundle size by 45mb.

Wino.Synchronization/Http/GmailClientMessageHandler.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Google.Apis.Http;
+using Wino.Domain.Entities;
+
+namespace Wino.Core.Http
+{
+    internal class GmailClientMessageHandler : ConfigurableMessageHandler
+    {
+        public Func<Task<TokenInformation>> TokenRetrieveDelegate { get; }
+
+        public GmailClientMessageHandler(Func<Task<TokenInformation>> tokenRetrieveDelegate) : base(new HttpClientHandler())
+        {
+            TokenRetrieveDelegate = tokenRetrieveDelegate;
+        }
+
+        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            var tokenizationTask = TokenRetrieveDelegate.Invoke();
+            var tokenInformation = await tokenizationTask;
+
+            request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", tokenInformation.AccessToken);
+
+            return await base.SendAsync(request, cancellationToken);
+        }
+    }
+}

Wino.Synchronization/Http/MicrosoftImmutableIdHandler.cs

@@ -0,0 +1,19 @@
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Wino.Core.Http
+{
+    /// <summary>
+    /// Adds additional Prefer header for immutable id support in the Graph service client.
+    /// </summary>
+    public class MicrosoftImmutableIdHandler : DelegatingHandler
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            request.Headers.TryAddWithoutValidation("Prefer", "IdType=\"ImmutableId\"");
+
+            return base.SendAsync(request, cancellationToken);
+        }
+    }
+}

Wino.Synchronization/Http/MicrosoftTokenProvider.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Kiota.Abstractions.Authentication;
+using Wino.Domain.Entities;
+using Wino.Domain.Interfaces;
+
+namespace Wino.Core.Http
+{
+    public class MicrosoftTokenProvider : IAccessTokenProvider
+    {
+        private readonly MailAccount _account;
+        private readonly IAuthenticator _authenticator;
+
+        public MicrosoftTokenProvider(MailAccount account, IAuthenticator authenticator)
+        {
+            _account = account;
+            _authenticator = authenticator;
+        }
+
+        public AllowedHostsValidator AllowedHostsValidator { get; }
+
+        public async Task<string> GetAuthorizationTokenAsync(Uri uri,
+                                                             Dictionary<string, object> additionalAuthenticationContext = null,
+                                                             CancellationToken cancellationToken = default)
+        {
+            var token = await _authenticator.GetTokenAsync(_account).ConfigureAwait(false);
+
+            return token?.AccessToken;
+        }
+    }
+}