Use TimeTicks instead of gettimeofday in ProcessMetrics.

base/process/process_metrics_linux.cc

 // 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.
 
 #include "base/process/process_metrics.h"
 
 #include <dirent.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/time.h>
@@ skipping 163 matching lines @@
 
 bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
 #if defined(OS_CHROMEOS)
   if (GetWorkingSetKBytesTotmaps(ws_usage))
     return true;
 #endif
   return GetWorkingSetKBytesStatm(ws_usage);
 }
 
 double ProcessMetrics::GetCPUUsage() {
-  struct timeval now;
-  int retval = gettimeofday(&now, NULL);
-  if (retval)
-    return 0;
-  int64 time = TimeValToMicroseconds(now);
+  TimeTicks time = TimeTicks::Now();
 
-  if (last_cpu_time_ == 0) {
+  if (last_cpu_ == 0) {
     // First call, just set the last values.
-    last_cpu_time_ = time;
+    last_cpu_walltime_ = time;
     last_cpu_ = GetProcessCPU(process_);
     return 0;
   }
 
-  int64 time_delta = time - last_cpu_time_;
+  int64 time_delta = (time - last_cpu_walltime_).InMicroseconds();
   DCHECK_NE(time_delta, 0);
   if (time_delta == 0)
     return 0;
 
   int cpu = GetProcessCPU(process_);
 
   // We have the number of jiffies in the time period.  Convert to percentage.
   // Note this means we will go *over* 100 in the case where multiple threads
   // are together adding to more than one CPU's worth.
   TimeDelta cpu_time = internal::ClockTicksToTimeDelta(cpu);
   TimeDelta last_cpu_time = internal::ClockTicksToTimeDelta(last_cpu_);
   int percentage = 100 * (cpu_time - last_cpu_time).InSecondsF() /
       TimeDelta::FromMicroseconds(time_delta).InSecondsF();
 
-  last_cpu_time_ = time;
+  last_cpu_walltime_ = time;
   last_cpu_ = cpu;
 
   return percentage;
 }
 
 // To have /proc/self/io file you must enable CONFIG_TASK_IO_ACCOUNTING
 // in your kernel configuration.
 bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
   // Synchronously reading files in /proc is safe.
   ThreadRestrictions::ScopedAllowIO allow_io;
@@ skipping 32 matching lines @@
         }
         state = KEY_NAME;
         break;
     }
   }
   return true;
 }
 
 ProcessMetrics::ProcessMetrics(ProcessHandle process)
     : process_(process),
-      last_cpu_time_(0),
       last_system_time_(0),
       last_cpu_(0) {
   processor_count_ = base::SysInfo::NumberOfProcessors();
 }
 
 #if defined(OS_CHROMEOS)
 // Private, Shared and Proportional working set sizes are obtained from
 // /proc/<pid>/totmaps
 bool ProcessMetrics::GetWorkingSetKBytesTotmaps(WorkingSetKBytes *ws_usage)
   const {
@@ skipping 598 matching lines @@
   swap_info->num_reads = ReadFileToUint64(zram_path.Append("num_reads"));
   swap_info->num_writes = ReadFileToUint64(zram_path.Append("num_writes"));
   swap_info->compr_data_size =
       ReadFileToUint64(zram_path.Append("compr_data_size"));
   swap_info->mem_used_total =
       ReadFileToUint64(zram_path.Append("mem_used_total"));
 }
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace base