Move IsRunningOnChromeOS to base/chromeos

base/chromeos/chromeos_version.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 "chrome/browser/chromeos/system/runtime_environment.h"
+#include "base/chromeos/chromeos_version.h"
 
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/logging.h"
 
+namespace base {
 namespace chromeos {
-namespace system {
-namespace runtime_environment {
 
 bool IsRunningOnChromeOS() {
   // Check if the user name is chronos. Note that we don't go with
   // getuid() + getpwuid_r() as it may end up reading /etc/passwd, which
   // can be expensive.
   const char* user = getenv("USER");
   return user && strcmp(user, "chronos") == 0;
 }
 
-}  // namespace runtime_environment
-}  // namespace system
 }  // namespace chromeos
+}  // namespace base