Add in obsolete HandleResized for ApiCompat.

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -31,7 +31,6 @@ MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDownV
 MembersMustExist : Member 'public Avalonia.StyledProperty<System.Boolean> Avalonia.StyledProperty<System.Boolean> Avalonia.Controls.ScrollViewer.AllowAutoHideProperty' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'protected void Avalonia.Controls.TopLevel.HandleResized(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.Controls.Viewbox.StretchProperty' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'protected void Avalonia.Controls.Window.HandleResized(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'protected void Avalonia.Controls.WindowBase.HandleResized(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.EventHandler<Avalonia.Controls.ApplicationLifetimes.ShutdownRequestedEventArgs> Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.ShutdownRequested' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.add_ShutdownRequested(System.EventHandler<Avalonia.Controls.ApplicationLifetimes.ShutdownRequestedEventArgs>)' is present in the implementation but not in the contract.
@@ -58,4 +57,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platfor
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size)' is present in the contract but not in the implementation.
 MembersMustExist : Member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size, Avalonia.Platform.PlatformResizeReason)' is present in the implementation but not in the contract.
-Total Issues: 59
+Total Issues: 58

src/Avalonia.Controls/Window.cs

@@ -949,6 +949,9 @@ namespace Avalonia.Controls
             Owner = null;
         }
 
+        [Obsolete("Use HandleResized(Size, PlatformResizeReason)")]
+        protected void HandleResized(Size clientSize) => HandleResized(clientSize, PlatformResizeReason.Unspecified);
+
         /// <inheritdoc/>
         protected sealed override void HandleResized(Size clientSize, PlatformResizeReason reason)
         {