Index: Src/GoogleApis.Auth.DotNet4/OAuth2/GoogleWebAuthenticationBroker.cs
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+/*
+Copyright 2013 Google Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Google.Apis.Util.Store;
+
+namespace Google.Apis.Auth.OAuth2
+{
+    /// <summary>A helper utility to manage the authorization code flow.</summary>
+    public class GoogleWebAuthenticationBroker
+    {
+        /// <summary>The folder which is used by the <seealso cref="Google.Apis.Util.Store.FileDataStore"/>.</summary>
+        public static string Folder = "Google.Apis.Auth";
+
+        /// <summary>Asynchronously authenticates the specified user.</summary>
+        /// <remarks>
+        /// In case no data store is specified, <seealso cref="Google.Apis.Util.Store.FileDataStore"/> will be used by 
+        /// default.
+        /// </remarks>
+        /// <param name="clientSecrets">The client secrets.</param>
+        /// <param name="scopes">
+        /// The scopes which indicate the Google API access your application is requesting.
+        /// </param>
+        /// <param name="user">The user to authenticate.</param>
+        /// <param name="taskCancellationToken">Cancellation token to cancel an operation.</param>
+        /// <param name="dataStore">The data store, if not specified a file data store will be used.</param>
+        /// <returns>User credential.</returns>
+        public static async Task<UserCredential> AuthenticateAsync(ClientSecrets clientSecrets,
+            IEnumerable<string> scopes, string user, CancellationToken taskCancellationToken,
+            IDataStore dataStore = null)
+        {
+            var initializer = new GoogleAuthorizationCodeFlow.Initializer
+            {
+                ClientSecrets = clientSecrets,
+            };
+            return await AuthenticateAsyncCore(initializer, scopes, user, taskCancellationToken, dataStore);
+        }
+
+        /// <summary>Asynchronously authenticates the specified user.</summary>
+        /// <remarks>
+        /// In case no data store is specified, <seealso cref="Google.Apis.Util.Store.FileDataStore"/> will be used by 
+        /// default.
+        /// </remarks>
+        /// <param name="clientSecretsStream">
+        /// The client secrets stream. The authorization code flow constructor is responsible for disposing the stream.
+        /// </remarks>
+        /// <param name="scopes">
+        /// The scopes which indicate the Google API access your application is requesting.
+        /// </param>
+        /// <param name="user">The user to authenticate.</param>
+        /// <param name="taskCancellationToken">Cancellation token to cancel an operation.</param>
+        /// <param name="dataStore">The data store, if not specified a file data store will be used.</param>
+        /// <returns>User credential.</returns>
+        public static async Task<UserCredential> AuthenticateAsync(Stream clientSecretsStream,
+            IEnumerable<string> scopes, string user, CancellationToken taskCancellationToken,
+            IDataStore dataStore = null)
+        {
+            var initializer = new GoogleAuthorizationCodeFlow.Initializer
+            {
+                ClientSecretsStream = clientSecretsStream,
+            };
+            return await AuthenticateAsyncCore(initializer, scopes, user, taskCancellationToken, dataStore);
+        }
+
+        /// <summary>The core logic for asynchronously authenticating the specified user.</summary>
+        /// <param name="initializer">The authorization code initializer.</param>
+        /// <param name="scopes">
+        /// The scopes which indicate the Google API access your application is requesting.
+        /// </param>
+        /// <param name="user">The user to authenticate.</param>
+        /// <param name="taskCancellationToken">Cancellation token to cancel an operation.</param>
+        /// <param name="dataStore">The data store, if not specified a file data store will be used.</param>
+        /// <returns>User credential.</returns>
+        private static async Task<UserCredential> AuthenticateAsyncCore(AuthorizationCodeFlow.Initializer initializer,
+            IEnumerable<string> scopes, string user, CancellationToken taskCancellationToken,
+            IDataStore dataStore = null)
+        {
+            initializer.Scopes = scopes;
+            initializer.DataStore = dataStore ?? new FileDataStore(Folder);
+            var flow = new GoogleAuthorizationCodeFlow(initializer);
+
+            // Create authorization code installed app instance and authorize the user.
+            return await new AuthorizationCodeInstalledApp(flow, new LocalServerCodeReceiver()).Authorize
+                (user, taskCancellationToken);
+        }
+    }
+}
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