Improve and unify Mac OS X run-time version checks

base/sys_info.h

 // Copyright (c) 2011 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.
 
 #ifndef BASE_SYS_INFO_H_
 #define BASE_SYS_INFO_H_
 #pragma once
 
 #include "base/base_api.h"
 #include "base/basictypes.h"
@@ skipping 23 matching lines @@
 
   // Returns the name of the host operating system.
   static std::string OperatingSystemName();
 
   // Returns the version of the host operating system.
   static std::string OperatingSystemVersion();
 
   // Retrieves detailed numeric values for the OS version.
   // TODO(port): Implement a Linux version of this method and enable the
   // corresponding unit test.
+  // DON'T USE THIS ON THE MAC to determine the current OS release for
+  // OS version-specific feature checks and workarounds. If you must use
+  // an OS version check instead of a feature check, use the base::mac::IsOS*
+  // family from base/mac/mac_util.h.
   static void OperatingSystemVersionNumbers(int32* major_version,
                                             int32* minor_version,
                                             int32* bugfix_version);
 
   // Returns the CPU architecture of the system. Exact return value may differ
   // across platforms.
   static std::string CPUArchitecture();
 
   // Returns the pixel dimensions of the primary display via the
   // width and height parameters.
@@ skipping 21 matching lines @@
   static void ParseLsbRelease(const std::string& lsb_release,
                               int32* major_version,
                               int32* minor_version,
                               int32* bugfix_version);
 #endif
 };
 
 }  // namespace base
 
 #endif  // BASE_SYS_INFO_H_