<phone:WebBrowser Name="webBrowser" Navigated="webBrowser_Navigated" Grid.ColumnSpan="2" IsScriptEnabled="True" />

<phone:PhoneApplicationPage 
    x:Class="FacebookTest.MainPage" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone" 
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="696" 
    FontFamily="{StaticResource PhoneFontFamilyNormal}" 
    FontSize="{StaticResource PhoneFontSizeNormal}" 
    Foreground="{StaticResource PhoneForegroundBrush}" 
    SupportedOrientations="Portrait" Orientation="Portrait" 
    shell:SystemTray.IsVisible="True">

    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition/>
        </Grid.RowDefinitions>

        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="SOFTBUILD" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="FacebookTest" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="0.329*"/>
                <ColumnDefinition Width="0.671*"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="0.8*"/>
                <RowDefinition Height="0.1*"/>
                <RowDefinition Height="0.1*"/>
            </Grid.RowDefinitions>
            <phone:WebBrowser Name="webBrowser" Navigated="webBrowser_Navigated" Grid.ColumnSpan="2" IsScriptEnabled="True" />
            <TextBlock Grid.Row="1" TextWrapping="Wrap" Text="AccessToken" d:LayoutOverrides="Width" VerticalAlignment="Center" Margin="12,0,0,0"/>
            <TextBlock Grid.Row="2" TextWrapping="Wrap" Text="Name" VerticalAlignment="Center" Margin="12,0,0,0"/>
            <TextBlock x:Name="textAccessToken" HorizontalAlignment="Left" Grid.Row="1" TextWrapping="Wrap" VerticalAlignment="Center" Margin="8,0,0,0" Grid.Column="1"/>
            <TextBlock x:Name="textName" HorizontalAlignment="Left" Grid.Row="2" TextWrapping="Wrap" VerticalAlignment="Center" Margin="8,0,0,0" Grid.Column="1"/>
        </Grid>
    </Grid>

    <phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
            <shell:ApplicationBarIconButton IconUri="/icons/appbar.share.rest.png" Text="Update Statues"/>
            <shell:ApplicationBarIconButton IconUri="/icons/appbar.upload.rest.png" Text="Upload"/> 
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>

</phone:PhoneApplicationPage>

using System.Collections.Generic;
using System.Diagnostics;
using System.Windows.Navigation;
using Facebook;
using Microsoft.Phone.Controls;

namespace FacebookTest {
    public partial class MainPage : PhoneApplicationPage {
        public MainPage() {
            InitializeComponent();
        }

        // アプリケーション キー
        private readonly string ApplicationID = "取得したアプリキー";
        private readonly string ApplicationSecret = "取得したシークレットキー";
        // アクセストークンを保持する
        string accessToken = "";

        protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e) {
            var oauthClient = new FacebookOAuthClient { AppId = ApplicationID };
            var prams = new Dictionary<string, object>();
            prams["response_type"] = "code";
            prams["scope"] = "user_about_me,user_photos,offline_access";

            // 認証用のページURLを取得
            var url = oauthClient.GetLoginUrl(prams);

            // 認証ページへ遷移
            webBrowser.Navigate(url);
        }

        private void webBrowser_Navigated(object sender, NavigationEventArgs e) {
            Debug.WriteLine("webBrowser_Navigated: {0}", e.Uri);

            FacebookOAuthResult oauthResult;
            if (!FacebookOAuthResult.TryParse(e.Uri, out oauthResult) || !oauthResult.IsSuccess) {
                return;
            }

            var oauthClient = new FacebookOAuthClient { AppId = ApplicationID };
            oauthClient.AppSecret = ApplicationSecret;
            var code = oauthResult.Code;

            // アクセストークンを要求(非同期実行)
            oauthClient.ExchangeCodeForAccessTokenCompleted += oauthClient_ExchangeCodeForAccessTokenCompleted;
            oauthClient.ExchangeCodeForAccessTokenAsync(code);
        }

        // アクセストークンを取得
        void oauthClient_ExchangeCodeForAccessTokenCompleted(object sender, FacebookApiEventArgs e) {
            var result = e.GetResultData() as IDictionary<string, object>;
            if (result == null) return;

            accessToken = (string)result["access_token"];

            Dispatcher.BeginInvoke(() => {
                textAccessToken.Text = accessToken;
            });
        }
    }
}