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

cc/trees/layer_tree_host_unittest_animation.cc

 // Copyright 2012 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/trees/layer_tree_host.h"
 
 #include <stdint.h>
 #include <climits>
 
 #include "cc/animation/animation_curve.h"
@@ skipping 793 matching lines @@
           scroll_layer_->element_id());
       EXPECT_TRUE(
           animation_host()->scroll_offset_animations().HasUpdatesForTesting());
     }
   }
 
   void WillCommitCompleteOnThread(LayerTreeHostImpl* host_impl) override {
     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());
     }
   }
 
   void NotifyAnimationTakeover(base::TimeTicks monotonic_time,
                                TargetProperty::Type target_property,
                                double animation_start_time,
                                std::unique_ptr<AnimationCurve> curve) override {
     EndTest();
   }
 
@@ skipping 74 matching lines @@
       EXPECT_EQ(gfx::ScrollOffset(10.f, 20.f),
                 curve->GetValue(base::TimeDelta()));
       EXPECT_EQ(gfx::ScrollOffset(650.f, 750.f), curve->target_value());
     }
   }
 
   void WillCommitCompleteOnThread(LayerTreeHostImpl* host_impl) override {
     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());
     }
   }
 
   void CommitCompleteOnThread(LayerTreeHostImpl* host_impl) override {
     if (host_impl->sync_tree()->source_frame_number() == 1) {
       Animation* animation = ScrollOffsetPlayer(*host_impl, scroll_layer_)
                                  .GetAnimation(TargetProperty::SCROLL_OFFSET);
       DCHECK(animation);
       ScrollOffsetAnimationCurve* curve =
           animation->curve()->ToScrollOffsetAnimationCurve();
@@ skipping 1047 matching lines @@
  private:
   scoped_refptr<Layer> layer_;
   FakeContentLayerClient client_;
 };
 
 MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestRebuildPropertyTreesOnAnimationSetNeedsCommit);
 
 }  // namespace
 }  // namespace cc