Simple cleanup.

base/system_monitor.cc

Index: base/system_monitor.cc
===================================================================
--- base/system_monitor.cc	(revision 23214)
+++ base/system_monitor.cc	(working copy)
@@ -5,6 +5,7 @@
 #include "base/system_monitor.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
+#include "base/singleton.h"
 
 namespace base {
 
@@ -72,6 +73,14 @@
   observer_list_->Notify(&PowerObserver::OnResume, this);
 }
 
+// static
+SystemMonitor* SystemMonitor::Get() {
+  // Uses the LeakySingletonTrait because cleanup is optional.
+  return
+      Singleton<SystemMonitor, LeakySingletonTraits<SystemMonitor> >::get();
+}
+
+// static
 void SystemMonitor::Start() {
 #if defined(ENABLE_BATTERY_MONITORING)
   DCHECK(MessageLoop::current());  // Can't call start too early.