How to disable bounce effect for ScrollViewer when content is not scrollable

ScrollContent.cs

using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Media;

namespace Kinnara.Phone.Controls
{
    public sealed class ScrollContent : ContentPresenter
    {
        private ScrollViewer _scrollOwner;
        private bool _isScrollClient;
        private ScrollBarVisibility _originalVerticalScrollBarVisibility;
        private Size _contentDesiredSize;

        protected override Size MeasureOverride(Size availableSize)
        {
            InitializeScrollOwner();

            if (_scrollOwner != null && !_isScrollClient)
            {
                _contentDesiredSize = base.MeasureOverride(new Size(availableSize.Width, double.PositiveInfinity));
            }
            else
            {
                _contentDesiredSize = base.MeasureOverride(availableSize);
            }

            UpdateVerticalScrollBarVisibility();

            return _contentDesiredSize;
        }

        private void InitializeScrollOwner()
        {
            if (_scrollOwner == null)
            {
                _scrollOwner = GetParentByType<ScrollViewer>(this);
                if (_scrollOwner != null)
                {
                    var itemsPresenter = _scrollOwner.Content as ItemsPresenter;
                    if (itemsPresenter != null)
                    {
                        if (VisualTreeHelper.GetChildrenCount(itemsPresenter) > 0)
                        {
                            var scrollInfo = VisualTreeHelper.GetChild(itemsPresenter, 0) as IScrollInfo;
                            if (scrollInfo != null)
                            {
                                _isScrollClient = true;
                            }
                        }
                    }

                    _originalVerticalScrollBarVisibility = _scrollOwner.VerticalScrollBarVisibility;

                    _scrollOwner.SizeChanged += OnScrollOwnerSizeChanged;
                }
            }
        }

        private void OnScrollOwnerSizeChanged(object sender, SizeChangedEventArgs e)
        {
            UpdateVerticalScrollBarVisibility();
        }

        private void UpdateVerticalScrollBarVisibility()
        {
            if (_isScrollClient)
            {
                if (_scrollOwner.ScrollableHeight > 0)
                {
                    SetVerticalScrollBarVisibility(_originalVerticalScrollBarVisibility);
                }
                else
                {
                    SetVerticalScrollBarVisibility(ScrollBarVisibility.Disabled);
                }
            }
            else if (_scrollOwner != null && _scrollOwner.ActualHeight > 0)
            {
                if (_scrollOwner.ViewportHeight < _contentDesiredSize.Height)
                {
                    SetVerticalScrollBarVisibility(_originalVerticalScrollBarVisibility);
                }
                else
                {
                    SetVerticalScrollBarVisibility(ScrollBarVisibility.Disabled);
                }
            }
        }

        private void SetVerticalScrollBarVisibility(ScrollBarVisibility value)
        {
            if (_scrollOwner.VerticalScrollBarVisibility != value)
            {
                _scrollOwner.VerticalScrollBarVisibility = value;
            }
        }

        private static T GetParentByType<T>(DependencyObject element)
            where T : FrameworkElement
        {
            Debug.Assert(element != null, "The element cannot be null.");

            T result = null;
            DependencyObject parent = VisualTreeHelper.GetParent(element);

            while (parent != null)
            {
                result = parent as T;

                if (result != null)
                {
                    return result;
                }

                parent = VisualTreeHelper.GetParent(parent);
            }

            return null;
        }
    }
}

XAML

<Style x:Key="ScrollViewerVerticalStyle" TargetType="ScrollViewer">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ScrollViewer">
                <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="ScrollStates">
                            <VisualStateGroup.Transitions>
                                <VisualTransition GeneratedDuration="00:00:00.5"/>
                            </VisualStateGroup.Transitions>
                            <VisualState x:Name="Scrolling">
                                <Storyboard>
                                    <DoubleAnimation Storyboard.TargetName="VerticalScrollBar" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="NotScrolling">
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Grid Margin="{TemplateBinding Padding}">
                        <ScrollContentPresenter x:Name="ScrollContentPresenter">
                            <ScrollContentPresenter.ContentTemplate>
                                <DataTemplate>
                                    <kpc:ScrollContent Content="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}" xmlns:kpc="clr-namespace:Kinnara.Phone.Controls"/>
                                </DataTemplate>
                            </ScrollContentPresenter.ContentTemplate>
                        </ScrollContentPresenter>
                        <ScrollBar x:Name="VerticalScrollBar" IsHitTestVisible="False" Opacity="0" Height="Auto" Width="5" HorizontalAlignment="Right" VerticalAlignment="Stretch" Margin="0,0,1,0" Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" IsTabStop="False" Maximum="{TemplateBinding ScrollableHeight}" Minimum="0" Value="{TemplateBinding VerticalOffset}" Orientation="Vertical" ViewportSize="{TemplateBinding ViewportHeight}" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style TargetType="ScrollViewer" BasedOn="{StaticResource ScrollViewerVerticalStyle}"/>