Remove IValueFrame.

And use the concrete `ValueFrame` (renamed from `ValueFrameBase`) as this was the only implementation of the interface.

src/Avalonia.Base/PropertyStore/BindingEntry.cs

@@ -9,14 +9,14 @@ namespace Avalonia.PropertyStore
         IObserver<object?>,
         IDisposable
     {
-        private readonly ValueFrameBase _frame;
+        private readonly ValueFrame _frame;
         private readonly IObservable<object?> _source;
         private IDisposable? _subscription;
         private bool _hasValue;
         private object? _value;
 
         public BindingEntry(
-            ValueFrameBase frame,
+            ValueFrame frame,
             AvaloniaProperty property,
             IObservable<object?> source)
         {

src/Avalonia.Base/PropertyStore/BindingEntry`1.cs

@@ -12,14 +12,14 @@ namespace Avalonia.PropertyStore
         IObserver<BindingValue<T>>,
         IDisposable
     {
-        private readonly ValueFrameBase _frame;
+        private readonly ValueFrame _frame;
         private readonly object _source;
         private IDisposable? _subscription;
         private bool _hasValue;
         private T? _value;
 
         public BindingEntry(
-            ValueFrameBase frame,
+            ValueFrame frame,
             StyledPropertyBase<T> property,
             IObservable<BindingValue<T>> source)
         {
@@ -29,7 +29,7 @@ namespace Avalonia.PropertyStore
         }
 
         public BindingEntry(
-            ValueFrameBase frame,
+            ValueFrame frame,
             StyledPropertyBase<T> property,
             IObservable<T> source)
         {

src/Avalonia.Base/PropertyStore/IValueEntry.cs

@@ -3,7 +3,7 @@
 namespace Avalonia.PropertyStore
 {
     /// <summary>
-    /// Represents an untyped value entry in an <see cref="IValueFrame"/>.
+    /// Represents an untyped value entry in a <see cref="ValueFrame"/>.
     /// </summary>
     internal interface IValueEntry
     {

src/Avalonia.Base/PropertyStore/IValueEntry`1.cs

@@ -1,7 +1,7 @@
 namespace Avalonia.PropertyStore
 {
     /// <summary>
-    /// Represents a typed value entry in an <see cref="IValueFrame"/>.
+    /// Represents a typed value entry in a <see cref="ValueFrame"/>.
     /// </summary>
     internal interface IValueEntry<T> : IValueEntry
     {

src/Avalonia.Base/PropertyStore/IValueFrame.cs

@@ -1,56 +0,0 @@
-using System;
-using System.Diagnostics.CodeAnalysis;
-using Avalonia.Data;
-
-namespace Avalonia.PropertyStore
-{
-    /// <summary>
-    /// Represents a collection of property values in a <see cref="PropertyStore.ValueStore"/>.
-    /// </summary>
-    /// <remarks>
-    /// A value frame is an abstraction over the following sources of values in an
-    /// <see cref="AvaloniaObject"/>:
-    /// 
-    /// - A style
-    /// - Local values
-    /// - Animation values
-    /// </remarks>
-    internal interface IValueFrame : IDisposable
-    {
-        /// <summary>
-        /// Gets the number of value entries in the frame.
-        /// </summary>
-        int EntryCount { get; }
-
-        /// <summary>
-        /// Gets a value indicating whether the frame is active.
-        /// </summary>
-        bool IsActive { get; }
-
-        /// <summary>
-        /// Gets the value store that owns the frame.
-        /// </summary>
-        ValueStore? Owner { get; }
-
-        /// <summary>
-        /// Gets the frame's priority.
-        /// </summary>
-        BindingPriority Priority { get; }
-
-        /// <summary>
-        /// Retreives the frame's value entry with the specified index.
-        /// </summary>
-        IValueEntry GetEntry(int index);
-
-        /// <summary>
-        /// Sets the owner of the value frame.
-        /// </summary>
-        /// <param name="owner">The new owner.</param>
-        void SetOwner(ValueStore? owner);
-
-        /// <summary>
-        /// Tries to retreive the frame's value entry for the specified property.
-        /// </summary>
-        bool TryGetEntry(AvaloniaProperty property, [NotNullWhen(true)] out IValueEntry? entry);
-    }
-}

src/Avalonia.Base/PropertyStore/ImmediateValueFrame.cs

@@ -7,7 +7,7 @@ namespace Avalonia.PropertyStore
     /// Holds values in a <see cref="ValueStore"/> set by one of the SetValue or AddBinding
     /// overloads with non-LocalValue priority.
     /// </summary>
-    internal class ImmediateValueFrame : ValueFrameBase
+    internal class ImmediateValueFrame : ValueFrame
     {
         public ImmediateValueFrame(BindingPriority priority)
         {

src/Avalonia.Base/PropertyStore/UntypedBindingEntry.cs

@@ -10,14 +10,14 @@ namespace Avalonia.PropertyStore
         IObserver<object?>,
         IDisposable
     {
-        private readonly ValueFrameBase _frame;
+        private readonly ValueFrame _frame;
         private readonly IObservable<object?> _source;
         private IDisposable? _subscription;
         private bool _hasValue;
         private T? _value;
 
         public UntypedBindingEntry(
-            ValueFrameBase frame,
+            ValueFrame frame,
             StyledPropertyBase<T> property,
             IObservable<object?> source)
         {

src/Avalonia.Base/PropertyStore/ValueFrameBase.cs → src/Avalonia.Base/PropertyStore/ValueFrame.cs

@@ -5,7 +5,7 @@ using Avalonia.Utilities;
 
 namespace Avalonia.PropertyStore
 {
-    internal abstract class ValueFrameBase : IValueFrame
+    internal abstract class ValueFrame
     {
         private readonly AvaloniaPropertyValueStore<IValueEntry> _entries = new();
 

src/Avalonia.Base/PropertyStore/ValueStore.cs

@@ -11,7 +11,7 @@ namespace Avalonia.PropertyStore
 {
     internal class ValueStore
     {
-        private readonly List<IValueFrame> _frames = new();
+        private readonly List<ValueFrame> _frames = new();
         private Dictionary<int, IDisposable>? _localValueBindings;
         private Dictionary<AvaloniaProperty, EffectiveValue>? _effectiveValues;
         private int _inheritedValueCount;
@@ -22,7 +22,7 @@ namespace Avalonia.PropertyStore
 
         public AvaloniaObject Owner { get; }
         public ValueStore? InheritanceAncestor { get; private set; }
-        public IReadOnlyList<IValueFrame> Frames => _frames;
+        public IReadOnlyList<ValueFrame> Frames => _frames;
 
         public void BeginStyling() => ++_styling;
 
@@ -32,7 +32,7 @@ namespace Avalonia.PropertyStore
                 ReevaluateEffectiveValues();
         }
 
-        public void AddFrame(IValueFrame style)
+        public void AddFrame(ValueFrame style)
         {
             InsertFrame(style);
             ReevaluateEffectiveValues();
@@ -366,7 +366,7 @@ namespace Avalonia.PropertyStore
         /// </summary>
         /// <param name="property">The previously bound property.</param>
         /// <param name="frame">The frame which contained the binding.</param>
-        public void OnBindingCompleted(AvaloniaProperty property, IValueFrame frame)
+        public void OnBindingCompleted(AvaloniaProperty property, ValueFrame frame)
         {
             var priority = frame.Priority;
 
@@ -378,11 +378,11 @@ namespace Avalonia.PropertyStore
         }
 
         /// <summary>
-        /// Called by an <see cref="IValueFrame"/> when its <see cref="IValueFrame.IsActive"/>
+        /// Called by a <see cref="ValueFrame"/> when its <see cref="ValueFrame.IsActive"/>
         /// state changes.
         /// </summary>
         /// <param name="frame">The frame which produced the change.</param>
-        public void OnFrameActivationChanged(IValueFrame frame)
+        public void OnFrameActivationChanged(ValueFrame frame)
         {
             ReevaluateEffectiveValues();
         }
@@ -523,12 +523,12 @@ namespace Avalonia.PropertyStore
         }
 
         /// <summary>
-        /// Called by an <see cref="IValueFrame"/> to re-evaluate the effective value when a value
+        /// Called by a <see cref="ValueFrame"/> to re-evaluate the effective value when a value
         /// is removed.
         /// </summary>
         /// <param name="frame">The frame on which the change occurred.</param>
         /// <param name="property">The property whose value was removed.</param>
-        public void OnValueEntryRemoved(IValueFrame frame, AvaloniaProperty property)
+        public void OnValueEntryRemoved(ValueFrame frame, AvaloniaProperty property)
         {
             Debug.Assert(frame.IsActive);
 
@@ -548,7 +548,7 @@ namespace Avalonia.PropertyStore
             }
         }
 
-        public bool RemoveFrame(IValueFrame frame)
+        public bool RemoveFrame(ValueFrame frame)
         {
             if (_frames.Remove(frame))
             {
@@ -570,7 +570,7 @@ namespace Avalonia.PropertyStore
                 null);
         }
 
-        private void InsertFrame(IValueFrame frame)
+        private void InsertFrame(ValueFrame frame)
         {
             Debug.Assert(!_frames.Contains(frame));
 

src/Avalonia.Base/Styling/StyleBase.cs

@@ -81,7 +81,7 @@ namespace Avalonia.Styling
             return _resources?.TryGetResource(key, out result) ?? false;
         }
 
-        internal IValueFrame Attach(IStyleable target, IStyleActivator? activator)
+        internal ValueFrame Attach(IStyleable target, IStyleActivator? activator)
         {
             if (target is not AvaloniaObject ao)
                 throw new InvalidOperationException("Styles can only be applied to AvaloniaObjects.");

src/Avalonia.Base/Styling/StyleInstance.cs

@@ -10,13 +10,13 @@ namespace Avalonia.Styling
     /// Stores state for a <see cref="Style"/> that has been instanced on a control.
     /// </summary>
     /// <remarks>
-    /// <see cref="StyleInstance"/> implements the <see cref="IValueFrame"/> interface meaning that
-    /// it is injected directly into the value store of an <see cref="AvaloniaObject"/>. Depending
-    /// on the setters present on the style, it may be possible to share a single style instance
-    /// among all controls that the style is applied to; meaning that a single style instance can
+    /// <see cref="StyleInstance"/> is based on <see cref="ValueFrame"/> meaning that it is 
+    /// injected directly into the value store of an <see cref="AvaloniaObject"/>. Depending on
+    /// the setters present on the style, it may be possible to share a single style instance
+    /// among all controls that the style is applied to, meaning that a single style instance can
     /// apply to multiple controls.
     /// </remarks>
-    internal class StyleInstance : ValueFrameBase, IStyleInstance, IStyleActivatorSink, IDisposable
+    internal class StyleInstance : ValueFrame, IStyleInstance, IStyleActivatorSink, IDisposable
     {
         private readonly IStyleActivator? _activator;
         private List<ISetterInstance>? _setters;