Use GpuPreferences to avoid directly accessing switches in gpu related code

gpu/command_buffer/service/mailbox_manager.cc

Index: gpu/command_buffer/service/mailbox_manager.cc
diff --git a/gpu/command_buffer/service/mailbox_manager.cc b/gpu/command_buffer/service/mailbox_manager.cc
index e8432ed17c5873532abae09571ee7b61441f3839..2b667937669aef66f4ccebf8e12a9364e3b3ad4d 100644
--- a/gpu/command_buffer/service/mailbox_manager.cc
+++ b/gpu/command_buffer/service/mailbox_manager.cc
@@ -5,7 +5,7 @@
 #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"
 
@@ -14,11 +14,9 @@ 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