Use GpuPreferences to avoid directly accessing switches in gpu related code

gpu/command_buffer/service/mailbox_manager.cc

 // Copyright 2015 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 "gpu/command_buffer/service/mailbox_manager.h"
 
 #include "base/command_line.h"
-#include "gpu/command_buffer/service/gpu_switches.h"
+#include "gpu/command_buffer/service/gpu_preferences.h"
 #include "gpu/command_buffer/service/mailbox_manager_impl.h"
 #include "gpu/command_buffer/service/mailbox_manager_sync.h"
 
 namespace gpu {
 namespace gles2 {
 
 // static
 scoped_refptr<MailboxManager> MailboxManager::Create() {
-    if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-            switches::kEnableThreadedTextureMailboxes)) {
-      return scoped_refptr<MailboxManager>(new MailboxManagerSync);
-    }
-    return scoped_refptr<MailboxManager>(new MailboxManagerImpl);
+  if (GpuPreferences::GetInstance()->enable_threaded_texture_mailboxes)
+    return scoped_refptr<MailboxManager>(new MailboxManagerSync);
+  return scoped_refptr<MailboxManager>(new MailboxManagerImpl);
 }
 
 }  // namespage gles2
 }  // namespace gpu