Add CurrentProcessInfo::CreationTime() for Linux

base/process/internal_linux.h

 // Copyright (c) 2013 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.
 
 // This file contains internal routines that are called by other files in
 // base/process/.
 
 #ifndef BASE_PROCESS_LINUX_INTERNAL_H_
 #define BASE_PROCESS_LINUX_INTERNAL_H_
 
 #include "base/files/file_path.h"
 
 namespace base {
+
+class Time;
+class TimeDelta;
+
 namespace internal {
 
 // "/proc"
 extern const char kProcDir[];
 
 // "stat"
 extern const char kStatFile[];
 
 // Returns a FilePath to "/proc/pid".
 base::FilePath GetProcPidDir(pid_t pid);
@@ skipping 18 matching lines @@
 // If the ordering ever changes, carefully review functions that use these
 // values.
 enum ProcStatsFields {
   VM_COMM           = 1,   // Filename of executable, without parentheses.
   VM_STATE          = 2,   // Letter indicating the state of the process.
   VM_PPID           = 3,   // PID of the parent.
   VM_PGRP           = 4,   // Process group id.
   VM_UTIME          = 13,  // Time scheduled in user mode in clock ticks.
   VM_STIME          = 14,  // Time scheduled in kernel mode in clock ticks.
   VM_NUMTHREADS     = 19,  // Number of threads.
+  VM_STARTTIME      = 21,  // The time the process started in clock ticks.
   VM_VSIZE          = 22,  // Virtual memory size in bytes.
   VM_RSS            = 23,  // Resident Set Size in pages.
 };
 
 // Reads the |field_num|th field from |proc_stats|. Returns 0 on failure.
 // This version does not handle the first 3 values, since the first value is
 // simply |pid|, and the next two values are strings.
 int GetProcStatsFieldAsInt(const std::vector<std::string>& proc_stats,
                            ProcStatsFields field_num);
 
 // Same as GetProcStatsFieldAsInt(), but for size_t values.
 size_t GetProcStatsFieldAsSizeT(const std::vector<std::string>& proc_stats,
                                 ProcStatsFields field_num);
 
 // Convenience wrapper around GetProcStatsFieldAsInt(), ParseProcStats() and
 // ReadProcStats(). See GetProcStatsFieldAsInt() for details.
 int ReadProcStatsAndGetFieldAsInt(pid_t pid,
                                   ProcStatsFields field_num);
 
 // Same as ReadProcStatsAndGetFieldAsInt() but for size_t values.
 size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
                                        ProcStatsFields field_num);
 
+// Returns the time that the OS started. Clock ticks are relative to this.
+Time GetBootTime();
+
+// Converts Linux clock ticks to a wall time delta.
+TimeDelta ClockTicksToTimeDelta(int clock_ticks);
+
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_PROCESS_LINUX_INTERNAL_H_