Make SystemMonitor not a Singleton and move it out of base

chrome/browser/profile_manager.cc

Index: chrome/browser/profile_manager.cc
diff --git a/chrome/browser/profile_manager.cc b/chrome/browser/profile_manager.cc
index 2a20bdc2994503df4acc277108d96dda1d3827e7..9b66e3966a7aa9872fd4627368a4ae645fdb5bd8 100644
--- a/chrome/browser/profile_manager.cc
+++ b/chrome/browser/profile_manager.cc
@@ -42,11 +42,11 @@ void ProfileManager::ShutdownSessionServices() {
 }
 
 ProfileManager::ProfileManager() {
-  base::SystemMonitor::Get()->AddObserver(this);
+  SystemMonitor::Get()->AddObserver(this);
 }
 
 ProfileManager::~ProfileManager() {
-  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+  SystemMonitor* system_monitor = SystemMonitor::Get();
   if (system_monitor)
     system_monitor->RemoveObserver(this);