Make MonoMac platform use DefaultRenderTimer infrastructure in its RenderTimer.

src/OSX/Avalonia.MonoMac/MonoMacPlatform.cs

@@ -86,7 +86,7 @@ namespace Avalonia.MonoMac
             App = NSApplication.SharedApplication;
             UpdateActivationPolicy();
             s_renderLoop = new RenderLoop();
-            s_renderTimer = new RenderTimer(); //TODO: use CVDisplayLink
+            s_renderTimer = new RenderTimer(60); //TODO: use CVDisplayLink
             s_monoMacInitialized = true;
         }
 
@@ -136,4 +136,4 @@ namespace Avalonia
             return builder.UseWindowingSubsystem(MonoMac.MonoMacPlatform.Initialize, "MonoMac");
         }
     }
-}
+}

src/OSX/Avalonia.MonoMac/RenderTimer.cs

@@ -6,26 +6,23 @@ using MonoMac.Foundation;
 namespace Avalonia.MonoMac
 {
     //TODO: Switch to using CVDisplayLink
-    public class RenderTimer : IRenderTimer
+    public class RenderTimer : DefaultRenderTimer
     {
-        private readonly object _lock = new object();
-        private readonly IDisposable _timer;
+        public RenderTimer(int framesPerSecond) : base(framesPerSecond)
+        {
+        }
 
-        public RenderTimer()
+        protected override IDisposable StartCore(Action<long> tick)
         {
-            _timer = AvaloniaLocator.Current.GetService<IRuntimePlatform>().StartSystemTimer(new TimeSpan(0, 0, 0, 0, 1000 / 60),
+            return AvaloniaLocator.Current.GetService<IRuntimePlatform>().StartSystemTimer(
+                TimeSpan.FromSeconds(1.0 / FramesPerSecond),
                 () =>
                 {
-                    lock (_lock)
+                    using (new NSAutoreleasePool())
                     {
-                        using (new NSAutoreleasePool())
-                        {
-                            Tick?.Invoke(Environment.TickCount);
-                        }
+                        tick?.Invoke(Environment.TickCount);
                     }
                 });
         }
-
-        public event Action<long> Tick;
     }
 }