cc: Fix use-after-frees for LayerTreeHostAnimationTest.

cc/trees/layer_tree_host_unittest_animation.cc

Index: cc/trees/layer_tree_host_unittest_animation.cc
diff --git a/cc/trees/layer_tree_host_unittest_animation.cc b/cc/trees/layer_tree_host_unittest_animation.cc
index c0f63099fcc16ae4c3dddc5939910542fdab4a80..2bc7f141833819c9188139d61f9a385b853d8792 100644
--- a/cc/trees/layer_tree_host_unittest_animation.cc
+++ b/cc/trees/layer_tree_host_unittest_animation.cc
@@ -1344,12 +1344,14 @@ class LayerTreeHostAnimationTestAddAnimationAfterAnimating
     if (host_impl->active_tree()->source_frame_number() < 2)
       return;
 
-    // Animation state is updated after drawing.
-    ImplThreadTaskRunner()->PostTask(
-        FROM_HERE,
-        base::Bind(&LayerTreeHostAnimationTestAddAnimationAfterAnimating::
-                       CheckAnimations,
-                   base::Unretained(this), host_impl));
+    // Animation state is updated after drawing. Only do this once.
+    if (!TestEnded()) {
+      ImplThreadTaskRunner()->PostTask(
+          FROM_HERE,
+          base::Bind(&LayerTreeHostAnimationTestAddAnimationAfterAnimating::
+                         CheckAnimations,
+                     base::Unretained(this), host_impl));
+    }
   }
 
   void CheckAnimations(LayerTreeHostImpl* host_impl) {