Convert the overlay scrollbar flag to use FeatureList

content/browser/site_per_process_browsertest.cc

Index: content/browser/site_per_process_browsertest.cc
diff --git a/content/browser/site_per_process_browsertest.cc b/content/browser/site_per_process_browsertest.cc
index 372a996ddada5fd957315f854e1b40ab1bf5e7bc..49add034105252313d453b108adf888d272a19a3 100644
--- a/content/browser/site_per_process_browsertest.cc
+++ b/content/browser/site_per_process_browsertest.cc
@@ -15,6 +15,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
@@ -87,7 +88,7 @@
 #include "ui/events/event_utils.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/latency/latency_info.h"
-#include "ui/native_theme/native_theme_switches.h"
+#include "ui/native_theme/native_theme_features.h"
 
 #if defined(USE_AURA)
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
@@ -622,9 +623,9 @@ void SitePerProcessBrowserTest::SetUpCommandLine(
 #if !defined(OS_ANDROID)
   // TODO(bokan): Needed for scrollability check in
   // FrameOwnerPropertiesPropagationScrolling. crbug.com/662196.
-  command_line->AppendSwitch(switches::kDisableOverlayScrollbar);
+  feature_list_.InitAndDisableFeature(features::kOverlayScrollbar);
 #endif
-};
+}
 
 void SitePerProcessBrowserTest::SetUpOnMainThread() {
   host_resolver()->AddRule("*", "127.0.0.1");