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

cc/animation/animation_host_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/animation/animation_host.h"
 
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_timeline.h"
 #include "cc/test/animation_test_common.h"
 #include "cc/test/animation_timelines_test_common.h"
@@ skipping 69 matching lines @@
   EXPECT_TRUE(host_impl->GetTimelineById(timeline_id2));
 }
 
 TEST_F(AnimationHostTest, ImplOnlyScrollAnimationUpdateTargetIfDetached) {
   client_.RegisterElement(element_id_, ElementListType::ACTIVE);
   client_impl_.RegisterElement(element_id_, ElementListType::PENDING);
 
   gfx::ScrollOffset target_offset(0., 2.);
   gfx::ScrollOffset current_offset(0., 1.);
   host_impl_->ImplOnlyScrollAnimationCreate(element_id_, target_offset,
-                                            current_offset, base::TimeDelta());
+                                            current_offset, base::TimeDelta(),
+                                            base::TimeDelta());
 
   gfx::Vector2dF scroll_delta(0, 0.5);
   gfx::ScrollOffset max_scroll_offset(0., 3.);
 
   base::TimeTicks time;
 
   time += base::TimeDelta::FromSecondsD(0.1);
   EXPECT_TRUE(host_impl_->ImplOnlyScrollAnimationUpdateTarget(
       element_id_, scroll_delta, max_scroll_offset, time, base::TimeDelta()));
 
   // Detach all players from layers and timelines.
   host_impl_->ClearMutators();
 
   time += base::TimeDelta::FromSecondsD(0.1);
   EXPECT_FALSE(host_impl_->ImplOnlyScrollAnimationUpdateTarget(
       element_id_, scroll_delta, max_scroll_offset, time, base::TimeDelta()));
 }
 
 }  // namespace
 }  // namespace cc