Web browser control

WebViewHostControl.xaml

<UserControl
    x:Class="MetroControls.WebViewHostControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:Converters="using:Metro.Controls.Converters" mc:Ignorable="d"
    d:DesignHeight="768"
    d:DesignWidth="320"
    VerticalAlignment="Stretch" HorizontalAlignment="Stretch">

    <UserControl.Resources>
        <Converters:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />

        <Style x:Key="MediumContentTextStyle" TargetType="TextBlock">
            <!-- style content omitted for brevity -->
        </Style>
        
    </UserControl.Resources>
    <Grid Opacity="0.8">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

<!-- HEADER -->
        <!-- Header area for panel: omitted for brevity -->

        <Grid Grid.Row="1" Margin="10">
            <WebView x:Name="webView" Visibility="Collapsed"/>
            <Rectangle x:Name="blockingRect" />
            <TextBlock x:Name="failedMessage" Text="{Binding FailedMessage}"
                       Style="{StaticResource MediumContentTextStyle}"
                       TextWrapping="Wrap" TextAlignment="Justify"
                       VerticalAlignment="Center" HorizontalAlignment="Center"
                       Visibility="Collapsed"/>
            <ProgressRing x:Name="progressRing" />
        </Grid>
        
    </Grid>
</UserControl>

WebViewHostControl.xaml.cs

    public sealed partial class WebViewHostControl : UserControl, INotifyPropertyChanged
    {
        //...

        public WebViewHostControl()
        {
            this.InitializeComponent();

            this.DataContext = this;

            webView.NavigationFailed += OnWebViewNavigationFailed;
            webView.LoadCompleted += OnWebViewLoadCompleted;

            this.Loaded += OnControlLoaded;
            this.Unloaded += OnControlUnLoaded;
        }

        private void OnControlUnLoaded(object sender, RoutedEventArgs e)
        {
            if (webView != null)
            {
                webView.LoadCompleted -= OnWebViewLoadCompleted;
                webView.NavigationFailed -= OnWebViewNavigationFailed;
            }
        }

        //...

        public string Uri
        {
            get { return _uri; }
            set
            {
                SetProperty(ref _uri, value);
            }
        }

        public string LocalFallbackUri
        {
            get { return _localFallbackUri; }
            set { SetProperty(ref _localFallbackUri, value); }
        }

        private void OnControlLoaded(object sender, RoutedEventArgs e)
        {
            if (!string.IsNullOrEmpty(Uri))
                NavigateAsync(Uri, false);
        }

        private void OnWebViewLoadCompleted(object sender, NavigationEventArgs e)
        {
            if (!_webViewNavigationFailed)
            {
                //Debug.WriteLine("Load completed, _webViewNavigationFailed is false");
                ShowWebView();
            }
        }

        private void OnWebViewNavigationFailed(object sender, WebViewNavigationFailedEventArgs e)
        {
            //try to get it from the local fallback uri
            _webViewNavigationFailed = true;
            //Debug.WriteLine("Nav failed: " + e.Uri + ", reason: " + e.WebErrorStatus);

            if (e.Uri.ToString() != LocalFallbackUri && !string.IsNullOrWhiteSpace(LocalFallbackUri))
                NavigateAsync(LocalFallbackUri, isLocal: true);
            else
                ShowLoadingFailedMessage();
        }

        private void ShowLoadingFailedMessage()
        {
            HideWebView(showProgress: false);
            failedMessage.Visibility = Visibility.Visible;
        }

        private async void NavigateAsync(string uri, bool isLocal = false)
        {
            HideWebView();
            try
            {
                //Debug.WriteLine("Navigating to " + uri);

                if (!isLocal)
                    webView.Navigate(new Uri(uri));
                else
                {
                    var file = await StorageFile.GetFileFromApplicationUriAsync(new Uri(uri));
                    var randomAccessStream = await file.OpenReadAsync();
                    using (var stream = randomAccessStream.AsStreamForRead())
                    {
                        using (var streamReader = new StreamReader(stream))
                        {
                            var fileContents = await streamReader.ReadToEndAsync();
                            if (!string.IsNullOrWhiteSpace(fileContents))
                            {
                                webView.NavigateToString(fileContents);
                            }
                        }
                    }
                }
                _webViewNavigationFailed = false;
            }
            catch (Exception ex)
            {
                //This should be replaced with proper runtime logging
                Debug.WriteLine("Error navigating: " + ex);
                ShowLoadingFailedMessage();
            }
        }

        //...
    }