CC Animation: Rework iterations over players to use the range-based for loop.

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 54c59a613f7458e461a6bdb2c1e4fa49d8b4338a..814a79389fc897a8b2a3b1e7e3acbdaa7444e90d 100644
--- a/cc/test/animation_timelines_test_common.cc
+++ b/cc/test/animation_timelines_test_common.cc
@@ -438,22 +438,16 @@ AnimationPlayer* AnimationTimelinesTest::GetPlayerForElementId(
     ElementId element_id) {
   const scoped_refptr<ElementAnimations> element_animations =
       host_->GetElementAnimationsForElementId(element_id);
-  return element_animations
-             ? ElementAnimations::PlayersList::Iterator(
-                   &element_animations->players_list())
-                   .GetNext()
-             : nullptr;
+  return element_animations ? &*element_animations->players_list().begin()
+                            : nullptr;
 }
 
 AnimationPlayer* AnimationTimelinesTest::GetImplPlayerForLayerId(
     ElementId element_id) {
   const scoped_refptr<ElementAnimations> element_animations =
       host_impl_->GetElementAnimationsForElementId(element_id);
-  return element_animations
-             ? ElementAnimations::PlayersList::Iterator(
-                   &element_animations->players_list())
-                   .GetNext()
-             : nullptr;
+  return element_animations ? &*element_animations->players_list().begin()
+                            : nullptr;
 }
 
 int AnimationTimelinesTest::NextTestLayerId() {