Manual revert of "Convert the overlay scrollbar flag to use FeatureList"

content/browser/android/content_startup_flags.cc

 // Copyright (c) 2012 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 "content/browser/android/content_startup_flags.h"
 
 #include "base/android/build_info.h"
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/sys_info.h"
 #include "cc/base/switches.h"
 #include "content/public/browser/android/compositor.h"
 #include "content/public/common/content_switches.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "ui/base/ui_base_switches.h"
+#include "ui/native_theme/native_theme_switches.h"
 
 namespace content {
 
 void SetContentCommandLineFlags(bool single_process,
                                 const std::string& plugin_descriptor) {
   // May be called multiple times, to cover all possible program entry points.
   static bool already_initialized = false;
   if (already_initialized)
     return;
   already_initialized = true;
 
   base::CommandLine* parsed_command_line =
       base::CommandLine::ForCurrentProcess();
 
   if (single_process) {
     // Need to ensure the command line flag is consistent as a lot of chrome
     // internal code checks this directly, but it wouldn't normally get set when
     // we are implementing an embedded WebView.
     parsed_command_line->AppendSwitch(switches::kSingleProcess);
   }
 
   parsed_command_line->AppendSwitch(switches::kEnablePinch);
   parsed_command_line->AppendSwitch(switches::kEnableViewport);
+  parsed_command_line->AppendSwitch(switches::kEnableOverlayScrollbar);
   parsed_command_line->AppendSwitch(switches::kValidateInputEventStream);
 
   if (base::android::BuildInfo::GetInstance()->sdk_int() >=
       base::android::SDK_VERSION_MARSHMALLOW) {
     parsed_command_line->AppendSwitch(switches::kEnableLongpressDragSelection);
     parsed_command_line->AppendSwitchASCII(
         switches::kTouchTextSelectionStrategy, "direction");
   }
 
   // There is no software fallback on Android, so don't limit GPU crashes.
@@ skipping 21 matching lines @@
   }
 
   // Disable profiler timing by default.
   if (!parsed_command_line->HasSwitch(switches::kProfilerTiming)) {
     parsed_command_line->AppendSwitchASCII(
         switches::kProfilerTiming, switches::kProfilerTimingDisabledValue);
   }
 }
 
 }  // namespace content