Added bounds at function OnGetBounds as reference

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "externals/skia"]
 	path = externals/skia
-	url = https://github.com/mono/skia.git
+	url = https://github.com/charlenni/skia.git
 	branch = xamarin-mobile-bindings
 [submodule "externals/depot_tools"]
 	path = externals/depot_tools

binding/Binding/SKAbstractDrawable.cs

@@ -14,7 +14,7 @@ namespace SkiaSharp
 		[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
 		internal delegate IntPtr draw_delegate (IntPtr managedDrawablePtr, IntPtr canvasPtr);
 		[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
-		internal delegate IntPtr getBounds_delegate (IntPtr managedDrawablePtr);
+		internal delegate IntPtr getBounds_delegate (IntPtr managedDrawablePtr, ref SKRect bounds);
 		[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
 		internal delegate IntPtr newPictureSnapshot_delegate (IntPtr managedDrawablePtr);
 
@@ -94,9 +94,10 @@ namespace SkiaSharp
 		}
 
 		[MonoPInvokeCallback(typeof(getBounds_delegate))]
-		private static IntPtr GetBoundsInternal (IntPtr managedDrawablePtr)
+		private static IntPtr GetBoundsInternal (IntPtr managedDrawablePtr, ref SKRect bounds)
 		{
-			return AsManagedDrawable (managedDrawablePtr).OnGetBounds ();
+			bounds = AsManagedDrawable (managedDrawablePtr).OnGetBounds ();
+			return IntPtr.Zero;
 		}
 
 		[MonoPInvokeCallback(typeof(newPictureSnapshot_delegate))]

externals/skia

@@ -1 +1 @@
-Subproject commit ce2dfd9d9820704200a8d9aa90d9c231e192b3d1
+Subproject commit a0eb0a12e4ef59ebc5a3a14b2c283aa7a979e877