Disable Overlay Scrollbar for CrOS M59

ui/native_theme/native_theme_features.cc

 // Copyright 2014 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 "ui/native_theme/native_theme_features.h"
 
 namespace features {
 
-#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
+#if defined(OS_ANDROID)
 constexpr base::FeatureState kOverlayScrollbarFeatureState =
     base::FEATURE_ENABLED_BY_DEFAULT;
 #else
 constexpr base::FeatureState kOverlayScrollbarFeatureState =
     base::FEATURE_DISABLED_BY_DEFAULT;
 #endif
 
 // Enables or disables overlay scrollbars in Blink (i.e. web content) on Aura
 // or Linux.  The status of native UI overlay scrollbars is determined in
 // PlatformStyle::CreateScrollBar. Does nothing on Mac.
 const base::Feature kOverlayScrollbar{"OverlayScrollbar",
                                       kOverlayScrollbarFeatureState};
 
 }  // namespace features
 
 namespace ui {
 
 bool IsOverlayScrollbarEnabled() {
   return base::FeatureList::IsEnabled(features::kOverlayScrollbar);
 }
 
 }  // namespace ui