ElementAnimations should hold an ObservableList of AnimationPlayers.

cc/test/animation_timelines_test_common.cc

Index: cc/test/animation_timelines_test_common.cc
diff --git a/cc/test/animation_timelines_test_common.cc b/cc/test/animation_timelines_test_common.cc
index e9377635582c17dcfc4ceeaad7445f4a76c15594..559feed217fa3b6ff5f0216e0f239747309174fb 100644
--- a/cc/test/animation_timelines_test_common.cc
+++ b/cc/test/animation_timelines_test_common.cc
@@ -495,16 +495,22 @@ AnimationPlayer* AnimationTimelinesTest::GetPlayerForElementId(
     ElementId element_id) {
   const scoped_refptr<ElementAnimations> element_animations =
       host_->GetElementAnimationsForElementId(element_id);
-  return element_animations ? element_animations->players_list().head()->value()
-                            : nullptr;
+  return element_animations
+             ? base::ObserverList<AnimationPlayer>::Iterator(

[loyso (OOO), 2016/08/05 00:18:48]

ElementAnimations::PlayersList type here and everywhere?

[ymalik, 2016/08/05 00:54:05]

Done.

+                   &element_animations->players_list())
+                   .GetNext()
+             : nullptr;
 }
 
 AnimationPlayer* AnimationTimelinesTest::GetImplPlayerForLayerId(
     ElementId element_id) {
   const scoped_refptr<ElementAnimations> element_animations =
       host_impl_->GetElementAnimationsForElementId(element_id);
-  return element_animations ? element_animations->players_list().head()->value()
-                            : nullptr;
+  return element_animations
+             ? base::ObserverList<AnimationPlayer>::Iterator(
+                   &element_animations->players_list())
+                   .GetNext()
+             : nullptr;
 }
 
 int AnimationTimelinesTest::NextTestLayerId() {