Add UMA for High Resolution Timer Usage

base/timer/hi_res_timer_manager_win.cc

Index: base/timer/hi_res_timer_manager_win.cc
diff --git a/base/timer/hi_res_timer_manager_win.cc b/base/timer/hi_res_timer_manager_win.cc
index 692f72b4e594481897bf022e256d51bb65b1f1b9..5474373e1bd935129bde3c1dcf11a6d132205d8e 100644
--- a/base/timer/hi_res_timer_manager_win.cc
+++ b/base/timer/hi_res_timer_manager_win.cc
@@ -4,21 +4,44 @@
 
 #include "base/timer/hi_res_timer_manager.h"
 
+#include <algorithm>
+
+#include "base/atomicops.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/power_monitor/power_monitor.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/time/time.h"
 
 namespace base {
 
+namespace {
+
+constexpr TimeDelta kUsageSampleInterval = TimeDelta::FromMinutes(10);
+
+void ReportHighResolutionTimerUsage() {
+  UMA_HISTOGRAM_PERCENTAGE("Windows.HighResolutionTimerUsage",
+                           Time::GetHighResolutionTimerUsage());
+  // Reset usage for the next interval.
+  Time::ResetHighResolutionTimerUsage();
+}
+
+}  // namespace
+
 HighResolutionTimerManager::HighResolutionTimerManager()
     : hi_res_clock_available_(false) {
-  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  PowerMonitor* power_monitor = PowerMonitor::Get();
   DCHECK(power_monitor != NULL);
   power_monitor->AddObserver(this);
   UseHiResClock(!power_monitor->IsOnBatteryPower());
+
+  // Start polling the high resolution timer usage.
+  Time::ResetHighResolutionTimerUsage();
+  timer_.Start(FROM_HERE, kUsageSampleInterval,
+               Bind(&ReportHighResolutionTimerUsage));
 }
 
 HighResolutionTimerManager::~HighResolutionTimerManager() {
-  base::PowerMonitor::Get()->RemoveObserver(this);
+  PowerMonitor::Get()->RemoveObserver(this);
   UseHiResClock(false);
 }
 
@@ -26,11 +49,22 @@ void HighResolutionTimerManager::OnPowerStateChange(bool on_battery_power) {
   UseHiResClock(!on_battery_power);
 }
 
+void HighResolutionTimerManager::OnSuspend() {
+  // Stop polling the usage to avoid including the standby time.
+  timer_.Stop();
+}
+
+void HighResolutionTimerManager::OnResume() {
+  // Resume polling the usage.
+  Time::ResetHighResolutionTimerUsage();
+  timer_.Reset();
+}
+
 void HighResolutionTimerManager::UseHiResClock(bool use) {
   if (use == hi_res_clock_available_)
     return;
   hi_res_clock_available_ = use;
-  base::Time::EnableHighResolutionTimer(use);
+  Time::EnableHighResolutionTimer(use);
 }
 
 }  // namespace base