cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

cc/input/scrollbar_animation_controller_thinning.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/input/scrollbar_animation_controller_thinning.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/scrollbar_layer_impl_base.h"
@@ skipping 64 matching lines @@
   captured_ = false;
 
   if (!mouse_is_over_scrollbar_)
     opacity_change_ = DECREASE;
   if (!mouse_is_near_scrollbar_)
     thickness_change_ = DECREASE;
   StartAnimation();
 }
 
 void ScrollbarAnimationControllerThinning::DidMouseMoveOffScrollbar() {
+  if (!mouse_is_over_scrollbar_ && !mouse_is_near_scrollbar_)
+    return;
+
   mouse_is_over_scrollbar_ = false;
   mouse_is_near_scrollbar_ = false;
 
   if (captured_)
     return;
 
   opacity_change_ = DECREASE;
   thickness_change_ = DECREASE;
   StartAnimation();
 }
@@ skipping 101 matching lines @@
           property_trees->effect_id_to_index_map[scrollbar->id()],
           scrollbar->layer_tree_impl());
     }
     scrollbar->SetThumbThicknessScaleFactor(AdjustScale(
         thumb_thickness_scale, scrollbar->thumb_thickness_scale_factor(),
         thickness_change_, kIdleThicknessScale, 1));
   }
 }
 
 }  // namespace cc