Make SystemMonitor not a Singleton and move it out of base

app/hi_res_timer_manager.h

+// Copyright (c) 2009 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.
+
+#ifndef APP_HI_RES_TIMER_MANAGER_H_
+#define APP_HI_RES_TIMER_MANAGER_H_
+
+#include "app/system_monitor.h"
+
+// Ensures that the Windows high resolution timer is only used
+// when not running on battery power.
+class HighResolutionTimerManager : public SystemMonitor::PowerObserver {
+ public:
+  HighResolutionTimerManager();
+  virtual ~HighResolutionTimerManager();
+
+  // SystemMonitor::PowerObserver:
+  void OnPowerStateChange(bool on_battery_power);
+
+ private:
+  // Enable or disable the faster multimedia timer.
+  void UseHiResClock(bool use);
+
+  bool hi_res_clock_used_;
+
+  DISALLOW_COPY_AND_ASSIGN(HighResolutionTimerManager);
+};
+
+#endif  // APP_HI_RES_TIMER_MANAGER_H_