Add UMA for High Resolution Timer Usage

base/timer/hi_res_timer_manager_unittest.cc

Index: base/timer/hi_res_timer_manager_unittest.cc
diff --git a/base/timer/hi_res_timer_manager_unittest.cc b/base/timer/hi_res_timer_manager_unittest.cc
index a0b0f9350ce2efc72303e49392c02870a20a14cf..18dd002b2dabe47a63a0f17f004d26ef4c7b3357 100644
--- a/base/timer/hi_res_timer_manager_unittest.cc
+++ b/base/timer/hi_res_timer_manager_unittest.cc
@@ -10,6 +10,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_monitor_device_source.h"
+#include "base/test/scoped_task_scheduler.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -22,6 +23,8 @@ TEST(HiResTimerManagerTest, ToggleOnOff) {
   // Windows, which makes this test flaky if you run while the machine
   // goes in or out of AC power.
   base::MessageLoop loop(base::MessageLoop::TYPE_UI);
+  // Needed for HighResolutionTimerManager.
+  base::test::ScopedTaskScheduler task_scheduler(&loop);

[gab, 2017/06/28 16:39:33]

ScopedTaskScheduler is deprecated. Please replace the MessageLoop with
base::test::ScopedTaskEnvironment instead.

[stanisc, 2017/06/28 22:28:35]

Done.

   std::unique_ptr<base::PowerMonitorSource> power_monitor_source(
       new base::PowerMonitorDeviceSource());
   std::unique_ptr<base::PowerMonitor> power_monitor(