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 116 matching lines @@
 
     if (mouse_is_near_scrollbar_ != mouse_is_near_scrollbar) {
       mouse_is_near_scrollbar_ = mouse_is_near_scrollbar;
       thickness_change_ = mouse_is_near_scrollbar_ ? INCREASE : DECREASE;
     }
 
     StartAnimation();
   }
 }
 
+void ScrollbarAnimationControllerThinning::DidMouseLeave() {
+  if (captured_)
+    return;
+
+  if (mouse_is_over_scrollbar_) {
+    mouse_is_over_scrollbar_ = false;
+    opacity_change_ = DECREASE;

[dtapuska, 2016/10/04 20:16:22]

Is it possible that the mouse_is_over_scrollbar_ and !mouse_is_near_scrollbar_ 
which then the animation to hide it never kicks off?

[chaopeng, 2016/10/04 20:48:10]

I have a issue have, should move StartAnimation out. 

+  }
+
+  if (mouse_is_near_scrollbar_) {
+    mouse_is_near_scrollbar_ = false;
+    thickness_change_ = DECREASE;
+
+    StartAnimation();
+  }
+}
+
 float ScrollbarAnimationControllerThinning::OpacityAtAnimationProgress(
     float progress) {
   if (opacity_change_ == NONE)
     return mouse_is_over_scrollbar_ ? 1.f : kIdleOpacity;
   float factor = opacity_change_ == INCREASE ? progress : (1.f - progress);
   float ret = ((1.f - kIdleOpacity) * factor) + kIdleOpacity;
   return ret;
 }
 
 float ScrollbarAnimationControllerThinning::
@@ skipping 49 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