C# Baseline function

Summary:
same as Measure function, based on #317
Closes https://github.com/facebook/yoga/pull/321

Reviewed By: emilsjolander

Differential Revision: D4385336

Pulled By: splhack

fbshipit-source-id: b583ec79861d2e9abba31a72503e2f706bfda8e8

csharp/tests/Facebook.Yoga/YogaNodeTest.cs

@@ -197,6 +197,54 @@ namespace Facebook.Yoga
             });
         }
 
+        [Test]
+        public void TestBaselineFunc()
+        {
+            YogaNode node = new YogaNode();
+            node.Height = 200;
+            node.FlexDirection = YogaFlexDirection.Row;
+            node.AlignItems = YogaAlign.Baseline;
+
+            YogaNode child0 = new YogaNode();
+            child0.Width = 100;
+            child0.Height = 110;
+            child0.SetBaselineFunction((_, width, height) => {
+                Assert.AreEqual(100, width);
+                Assert.AreEqual(110, height);
+                return 65;
+            });
+            node.Insert(0, child0);
+
+            YogaNode child1 = new YogaNode();
+            child1.Width = 100;
+            child1.Height = 110;
+            child1.SetBaselineFunction((_, width, height) => {
+                Assert.AreEqual(100, width);
+                Assert.AreEqual(110, height);
+                return 80;
+            });
+            node.Insert(1, child1);
+
+            YogaNode child2 = new YogaNode();
+            child2.Width = 100;
+            child2.Height = 110;
+            child2.SetBaselineFunction((_, width, height) => {
+                Assert.AreEqual(100, width);
+                Assert.AreEqual(110, height);
+                return 88;
+            });
+            node.Insert(2, child2);
+
+            node.CalculateLayout();
+
+            Assert.AreEqual(0, child0.LayoutX);
+            Assert.AreEqual(23, child0.LayoutY);
+            Assert.AreEqual(100, child1.LayoutX);
+            Assert.AreEqual(8, child1.LayoutY);
+            Assert.AreEqual(200, child2.LayoutX);
+            Assert.AreEqual(0, child2.LayoutY);
+        }
+
         [Test]
         public void TestPrint()
         {