Change cc::ElementId to be a uint64_t

cc/animation/animation_player_unittest.cc

Index: cc/animation/animation_player_unittest.cc
diff --git a/cc/animation/animation_player_unittest.cc b/cc/animation/animation_player_unittest.cc
index d896f21340238e226056295905f64f96b776a3fe..7b4b82d850f3f86437fbc8aaf63318780c6b198a 100644
--- a/cc/animation/animation_player_unittest.cc
+++ b/cc/animation/animation_player_unittest.cc
@@ -394,7 +394,7 @@ TEST_F(AnimationPlayerTest, SwitchToLayer) {
   EXPECT_EQ(player_impl_->element_id(), element_id_);
   EXPECT_TRUE(CheckPlayerTimelineNeedsPushProperties(false));
 
-  const ElementId new_element_id(NextTestLayerId(), 0);
+  const ElementId new_element_id(NextTestLayerId());
   player_->DetachElement();
   player_->AttachElement(new_element_id);