Implemented a "Last Updated" field for the about page of Chrome OS.

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_export.h"
 #include "base/basictypes.h"
+#include "base/time.h"
 
 #include <string>
 
 class FilePath;
 
 namespace base {
 
 class BASE_EXPORT SysInfo {
  public:
   // Return the number of logical processors/cores on the current machine.
@@ skipping 33 matching lines @@
   // across platforms.
   static std::string CPUArchitecture();
 
   // Return the smallest amount of memory (in bytes) which the VM system will
   // allocate.
   static size_t VMAllocationGranularity();
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   // Returns the maximum SysV shared memory segment size.
   static size_t MaxSharedMemorySize();
-#endif
+#endif // defined(OS_POSIX) && !defined(OS_MACOSX)
 
 #if defined(OS_CHROMEOS)
   // Returns the name of the version entry we wish to look up in the
   // Linux Standard Base release information file.
   static std::string GetLinuxStandardBaseVersionKey();
 
   // Parses /etc/lsb-release to get version information for Google Chrome OS.
   // Declared here so it can be exposed for unit testing.
   static void ParseLsbRelease(const std::string& lsb_release,
                               int32* major_version,
                               int32* minor_version,
                               int32* bugfix_version);
-#endif
+
+  // Retrieves the approximate time at which Chrome OS was last updated. Each
+  // time a new build is created, /etc/lsb-release is modified with the new
+  // version numbers of the release. This function reads that file's metadata
+  // and sets |time| equal to the time at which it was last modified, a close
+  // approximation to the time the last Chrome OS update occurred. On success,
+  // this function returns |true|, and if a problem is encountered, it returns
+  // |false|.
+  static bool GetTimeLastUpdated(base::Time* time);
+#endif // defined(OS_CHROMEOS)
 };
 
 }  // namespace base
 
 #endif  // BASE_SYS_INFO_H_