Experimental fix for scroll animation update bug. [DO NOT COMMIT THIS CHANGE]

cc/animation/scroll_offset_animations_impl.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_animations_impl.h"
 
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_player.h"
 #include "cc/animation/animation_timeline.h"
@@ skipping 80 matching lines @@
   base::TimeDelta trimmed =
       animation->run_state() == Animation::WAITING_FOR_TARGET_AVAILABILITY
           ? base::TimeDelta()
           : animation->TrimTimeToCurrentIteration(frame_monotonic_time);
 
   // Re-target taking the delay into account. Note that if the duration of the
   // animation is 0, trimmed will be 0 and UpdateTarget will be called with
   // t = -delayed_by.
   trimmed -= delayed_by;
 
+  double old_dur = curve->Duration().InMillisecondsF();
   curve->UpdateTarget(trimmed.InSecondsF(), new_target);
+  double new_dur = curve->Duration().InMillisecondsF();
 
-  return true;
+  return old_dur != new_dur;
 }
 
 void ScrollOffsetAnimationsImpl::ScrollAnimationApplyAdjustment(
     ElementId element_id,
     const gfx::Vector2dF& adjustment) {
   DCHECK(scroll_offset_animation_player_);
   if (element_id != scroll_offset_animation_player_->element_id())
     return;
 
   if (!scroll_offset_animation_player_->element_animations())
@@ skipping 43 matching lines @@
     ElementId element_id) {
   if (scroll_offset_animation_player_->element_id() != element_id) {
     if (scroll_offset_animation_player_->element_id())
       scroll_offset_animation_player_->DetachElement();
     if (element_id)
       scroll_offset_animation_player_->AttachElement(element_id);
   }
 }
 
 }  // namespace cc