Document bad pattern in base::SystemMonitor.

base/system_monitor/system_monitor.h

Index: base/system_monitor/system_monitor.h
diff --git a/base/system_monitor/system_monitor.h b/base/system_monitor/system_monitor.h
index 48d512b708c11aa44368c05300dd9a38f29e00ed..51b2364570ca923ae6fffc5ca42c38b0c3cc17aa 100644
--- a/base/system_monitor/system_monitor.h
+++ b/base/system_monitor/system_monitor.h
@@ -159,6 +159,10 @@ class BASE_EXPORT SystemMonitor {
   void RemovePowerObserver(PowerObserver* obs);
   void RemoveDevicesChangedObserver(DevicesChangedObserver* obs);
 
+  // The ProcessFoo() style methods are a broken pattern and should not
+  // be copied. Any significant addition to this class is blocked on
+  // refactoring to improve the state of affairs. See http://crbug.com/149059
+
 #if defined(OS_WIN)
   // Windows-specific handling of a WM_POWERBROADCAST message.
   // Embedders of this API should hook their top-level window