PathBasedAppBarButtonStyle

PathBasedAppBarButtonStyle.xaml

<Style x:Key="PathBasedAppBarButtonStyle" BasedOn="{StaticResource AppBarButtonStyle}" TargetType="ButtonBase">
    <Setter Property="ContentTemplate">
        <Setter.Value>
            <DataTemplate>
                <Path Width="20" Height="20" 
                        Stretch="Uniform" 
                        Fill="{Binding Path=Foreground, RelativeSource={RelativeSource Mode=TemplatedParent}}" 
                        Data="{Binding Path=Content, RelativeSource={RelativeSource Mode=TemplatedParent}}"/>
            </DataTemplate>
        </Setter.Value>
    </Setter>
</Style>