Update overlay scrollbars

cc/layers/scrollbar_layer_impl_base.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/layers/scrollbar_layer_impl_base.h"
 
 #include <algorithm>
 #include "cc/layers/layer.h"
 #include "ui/gfx/rect_conversions.h"
 
@@ skipping 48 matching lines @@
 }
 
 void ScrollbarLayerImplBase::SetVerticalAdjust(float vertical_adjust) {
   if (vertical_adjust_ == vertical_adjust)
     return;
   vertical_adjust_ = vertical_adjust;
   NoteLayerPropertyChanged();
 }
 
 void ScrollbarLayerImplBase::SetVisibleToTotalLengthRatio(float ratio) {
+  if (!IsThumbResizable())
+    return;
+
   if (visible_to_total_length_ratio_ == ratio)
     return;
   visible_to_total_length_ratio_ = ratio;
   NoteLayerPropertyChanged();
 }
 
 void ScrollbarLayerImplBase::SetThumbThicknessScaleFactor(float factor) {
   if (thumb_thickness_scale_factor_ == factor)
     return;
   thumb_thickness_scale_factor_ = factor;
@@ skipping 89 matching lines @@
             : thumb_thickness_adjustment,
         thumb_offset,
         thumb_thickness - thumb_thickness_adjustment,
         thumb_length);
   }
 
   return ScrollbarLayerRectToContentRect(thumb_rect);
 }
 
 }  // namespace cc