Revert 231699 "Remove kNaturalScrollDefault."

trunk/src/chrome/browser/chromeos/chrome_browser_main_chromeos.cc

 // Copyright (c) 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 "chrome/browser/chromeos/chrome_browser_main_chromeos.h"
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_switches.h"
@@ skipping 626 matching lines @@
 #endif
 
   // -- This used to be in ChromeBrowserMainParts::PreMainMessageLoopRun()
   // -- immediately after ChildProcess::WaitForDebugger().
 
   // Start the out-of-memory priority manager here so that we give the most
   // amount of time for the other services to start up before we start
   // adjusting the oom priority.
   g_browser_process->platform_part()->oom_priority_manager()->Start();
 
-  if (ui::ShouldDefaultToNaturalScroll())
+  if (ui::ShouldDefaultToNaturalScroll()) {
+    CommandLine::ForCurrentProcess()->AppendSwitch(
+        chromeos::switches::kNaturalScrollDefault);
     ui::SetNaturalScroll(true);
+  }
 
   ChromeBrowserMainPartsLinux::PreBrowserStart();
 }
 
 void ChromeBrowserMainPartsChromeos::PostBrowserStart() {
   // These are dependent on the ash::Shell singleton already having been
   // initialized.
   power_button_observer_.reset(new PowerButtonObserver);
   data_promo_notification_.reset(new DataPromoNotification()),
 
@@ skipping 103 matching lines @@
 
   // Destroy DeviceSettingsService after g_browser_process.
   DeviceSettingsService::Shutdown();
 }
 
 void ChromeBrowserMainPartsChromeos::SetupPlatformFieldTrials() {
   default_pinned_apps_field_trial::SetupTrial();
 }
 
 }  //  namespace chromeos