Fix bounds clamping during composited smooth scroll.

cc/animation/scroll_offset_animation_curve.cc

 // Copyright 2013 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/scroll_offset_animation_curve.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ skipping 164 matching lines @@
       old_normalized_velocity * old_delta_max_dimension / old_duration;
   double bound = (new_delta_max_dimension / old_true_velocity) * 2.5f;
 
   // If bound < 0 we are moving in the opposite direction.
   return bound < 0 ? std::numeric_limits<double>::infinity() : bound;
 }
 
 void ScrollOffsetAnimationCurve::UpdateTarget(
     double t,
     const gfx::ScrollOffset& new_target) {
+  if (std::abs(MaximumDimension(target_value_.DeltaFrom(new_target))) <
+      kEpsilon) {
+    target_value_ = new_target;
+    return;
+  }
   gfx::ScrollOffset current_position =
       GetValue(base::TimeDelta::FromSecondsD(t));
   gfx::Vector2dF old_delta = target_value_.DeltaFrom(initial_value_);
   gfx::Vector2dF new_delta = new_target.DeltaFrom(current_position);
 
   double old_duration =
       (total_animation_duration_ - last_retarget_).InSecondsF();
   double old_normalized_velocity = timing_function_->Velocity(
       (t - last_retarget_.InSecondsF()) / old_duration);
 
@@ skipping 20 matching lines @@
       (MaximumDimension(old_delta) / MaximumDimension(new_delta));
 
   initial_value_ = current_position;
   target_value_ = new_target;
   total_animation_duration_ = base::TimeDelta::FromSecondsD(t + new_duration);
   last_retarget_ = base::TimeDelta::FromSecondsD(t);
   timing_function_ = EaseOutWithInitialVelocity(new_normalized_velocity);
 }
 
 }  // namespace cc