Reverting this as it causes browser tests on the Linux ChromiumOS builder to fail.

chrome/browser/policy/config_dir_policy_loader.cc

Index: chrome/browser/policy/config_dir_policy_loader.cc
===================================================================
--- chrome/browser/policy/config_dir_policy_loader.cc	(revision 150390)
+++ chrome/browser/policy/config_dir_policy_loader.cc	(working copy)
@@ -13,11 +13,9 @@
 #include "base/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/logging.h"
-#include "base/message_loop.h"
 #include "base/platform_file.h"
 #include "base/stl_util.h"
 #include "chrome/browser/policy/policy_bundle.h"
-#include "content/public/browser/browser_thread.h"
 
 namespace policy {
 
@@ -38,13 +36,6 @@
 ConfigDirPolicyLoader::~ConfigDirPolicyLoader() {}
 
 void ConfigDirPolicyLoader::InitOnFile() {
-  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
-  // Some unit tests create a File thread that shares a MessageLoop with the
-  // UI thread, and this causes DCHECKs because IO operations aren't allowed on
-  // that thread. So if this is running in the context of one of those tests,
-  // just exit.
-  if (!MessageLoop::current()->IsType(MessageLoop::TYPE_IO))
-    return;
   base::files::FilePathWatcher::Callback callback =
       base::Bind(&ConfigDirPolicyLoader::OnFileUpdated, base::Unretained(this));
   mandatory_watcher_.Watch(config_dir_.Append(kMandatoryConfigDir), callback);