Revert 157168 - Add guards to metric values; erase bad events/metrics from db

chrome/browser/performance_monitor/performance_monitor.h

Index: chrome/browser/performance_monitor/performance_monitor.h
===================================================================
--- chrome/browser/performance_monitor/performance_monitor.h	(revision 157181)
+++ chrome/browser/performance_monitor/performance_monitor.h	(working copy)
@@ -131,9 +131,8 @@
   void AddEventOnBackgroundThread(scoped_ptr<Event> event);
 
   // Since Database::AddMetric() is overloaded, base::Bind() does not work and
-  // we need a helper function. Deliberately not const & so that we will
-  // construct a new metric on the background thread.
-  void AddMetricOnBackgroundThread(Metric metric);
+  // we need a helper function.
+  void AddMetricOnBackgroundThread(MetricType type, const std::string& value);
 
   // Notify any listeners that PerformanceMonitor has finished the initializing.
   void NotifyInitialized();