Reduce composited smooth scroll latency by a frame (also fixes latency UMAs).

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 1eefcfcce4b215ede748dc21e636ec0d5720235a..b9fa010f63274d703d7f8eed64859aba50a7a2b2 100644
--- a/cc/trees/layer_tree_host_unittest_animation.cc
+++ b/cc/trees/layer_tree_host_unittest_animation.cc
@@ -811,7 +811,7 @@ class LayerTreeHostAnimationTestScrollOffsetAnimationTakeover
     if (host_impl->sync_tree()->source_frame_number() == 0) {
       GetImplAnimationHost(host_impl)->ImplOnlyScrollAnimationCreate(
           scroll_layer_->element_id(), gfx::ScrollOffset(650.f, 750.f),
-          gfx::ScrollOffset(10, 20), base::TimeDelta());
+          gfx::ScrollOffset(10, 20), base::TimeDelta(), base::TimeDelta());
     }
   }
 
@@ -906,7 +906,7 @@ class LayerTreeHostAnimationTestScrollOffsetAnimationAdjusted
     if (host_impl->sync_tree()->source_frame_number() == 0) {
       GetImplAnimationHost(host_impl)->ImplOnlyScrollAnimationCreate(
           scroll_layer_->element_id(), gfx::ScrollOffset(650.f, 750.f),
-          gfx::ScrollOffset(10, 20), base::TimeDelta());
+          gfx::ScrollOffset(10, 20), base::TimeDelta(), base::TimeDelta());
     }
   }