Use TimeTicks instead of gettimeofday in ProcessMetrics.

base/process/process_metrics_mac.cc

Index: base/process/process_metrics_mac.cc
diff --git a/base/process/process_metrics_mac.cc b/base/process/process_metrics_mac.cc
index 61db9c2cadf585ff8512ff9ecccc3e3c29fe8bb5..6227ca2c67c4597df708a84d6a3b3e8c03185259 100644
--- a/base/process/process_metrics_mac.cc
+++ b/base/process/process_metrics_mac.cc
@@ -267,31 +267,26 @@ double ProcessMetrics::GetCPUUsage() {
   timeradd(&user_timeval, &task_timeval, &task_timeval);
   timeradd(&system_timeval, &task_timeval, &task_timeval);
 
-  struct timeval now;
-  int retval = gettimeofday(&now, NULL);
-  if (retval)
-    return 0;
-
-  int64 time = TimeValToMicroseconds(now);
+  TimeTicks time = TimeTicks::Now();
   int64 task_time = TimeValToMicroseconds(task_timeval);
 
-  if (last_cpu_time_ == 0) {
+  if (last_system_time_ == 0) {
     // First call, just set the last values.
-    last_cpu_time_ = time;
+    last_cpu_walltime_ = time;
     last_system_time_ = task_time;
     return 0;
   }
 
   int64 system_time_delta = task_time - last_system_time_;
-  int64 time_delta = time - last_cpu_time_;
-  DCHECK_NE(0U, time_delta);
-  if (time_delta == 0)
+  int64 walltime_delta = (time - last_cpu_walltime_).InMicroseconds();
+  DCHECK_NE(0U, walltime_delta);
+  if (walltime_delta == 0)
     return 0;
 
-  last_cpu_time_ = time;
+  last_cpu_walltime_ = time;
   last_system_time_ = task_time;
 
-  return static_cast<double>(system_time_delta * 100.0) / time_delta;
+  return static_cast<double>(system_time_delta * 100.0) / walltime_delta;
 }
 
 int ProcessMetrics::GetIdleWakeupsPerSecond() {
@@ -314,32 +309,28 @@ int ProcessMetrics::GetIdleWakeupsPerSecond() {
   }
   uint64_t absolute_idle_wakeups = power_info_data.task_platform_idle_wakeups;
 
-  struct timeval now;
-  int retval = gettimeofday(&now, NULL);
-  if (retval)
-    return 0;
-
-  int64 time = TimeValToMicroseconds(now);
+  TimeTicks time = TimeTicks::Now();
 
-  if (last_idle_wakeups_time_ == 0) {
+  if (last_absolute_idle_wakeups_ == 0) {
     // First call, just set the last values.
-    last_idle_wakeups_time_ = time;
+    last_idle_wakeups_walltime_ = time;
     last_absolute_idle_wakeups_ = absolute_idle_wakeups;
     return 0;
   }
 
   int64 wakeups_delta = absolute_idle_wakeups - last_absolute_idle_wakeups_;
-  int64 time_delta = time - last_idle_wakeups_time_;
-  DCHECK_NE(0U, time_delta);
-  if (time_delta == 0)
+  int64 walltime_delta = (time - last_idle_wakeups_walltime_).InMicroseconds();
+  DCHECK_NE(0U, walltime_delta);
+  if (walltime_delta == 0)
     return 0;
 
-  last_idle_wakeups_time_ = time;
+  last_idle_wakeups_walltime_ = time;
   last_absolute_idle_wakeups_ = absolute_idle_wakeups;
 
   // Round to average wakeups per second.
   const int kMicrosecondsPerSecond = 1000 * 1000;
-  return (wakeups_delta * kMicrosecondsPerSecond + time_delta/2) / time_delta;
+  return (wakeups_delta * kMicrosecondsPerSecond + walltime_delta / 2) /
+         walltime_delta;
 }
 
 bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
@@ -349,9 +340,7 @@ bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
 ProcessMetrics::ProcessMetrics(ProcessHandle process,
                                ProcessMetrics::PortProvider* port_provider)
     : process_(process),
-      last_cpu_time_(0),
       last_system_time_(0),
-      last_idle_wakeups_time_(0),
       last_absolute_idle_wakeups_(0),
       port_provider_(port_provider) {
   processor_count_ = SysInfo::NumberOfProcessors();