DStreetView.xaml

<UserControl x:Class="PAMStreetView.DStreetViewView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
			 xmlns:i="http://schemas.microsoft.com/xaml/behaviors"
             xmlns:extensions="clr-namespace:ArcGIS.Desktop.Extensions;assembly=ArcGIS.Desktop.Extensions"
             xmlns:frameworkControls="clr-namespace:ArcGIS.Desktop.Framework.Controls;assembly=ArcGIS.Desktop.Framework"
             xmlns:local="clr-namespace:PAMStreetView"
             mc:Ignorable="d"
             d:DesignHeight="300" d:DesignWidth="300">
    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="pack://application:,,,/ArcGIS.Desktop.Framework;component\Themes\Default.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <Grid>

        <DockPanel LastChildFill="true" KeyboardNavigation.TabNavigation="Local"  HorizontalAlignment="Stretch" VerticalAlignment="Stretch">

            <frameworkControls:WebViewBrowser Name="wbStreetView" Source="{Binding WebAddress}" local:SizeObserver.Observe="True" local:SizeObserver.ObservedWidth="{Binding WbWidth, Mode=OneWayToSource}" local:SizeObserver.ObservedHeight="{Binding WbHeight, Mode=OneWayToSource}" />

        </DockPanel>
        
        
    </Grid>
</UserControl>