Remove MetricsServiceObserver in favor of MetricsProvider.

chrome/browser/metrics/metrics_service_accessor.h

Index: chrome/browser/metrics/metrics_service_accessor.h
diff --git a/chrome/browser/metrics/metrics_service_accessor.h b/chrome/browser/metrics/metrics_service_accessor.h
index df2f3e0f49ddd9cd053aa4d00c4c03fe7efffe19..9d1438e11f7f9312e2d65eb80699add4006c6893 100644
--- a/chrome/browser/metrics/metrics_service_accessor.h
+++ b/chrome/browser/metrics/metrics_service_accessor.h
@@ -6,13 +6,11 @@
 #define CHROME_BROWSER_METRICS_METRICS_SERVICE_ACCESSOR_H_
 
 #include <stdint.h>
-#include <string>
 
 #include "base/macros.h"
 
 namespace metrics {
 class MetricsService;
-class MetricsServiceObserver;
 }
 
 // This class limits and documents access to metrics service helper methods.
@@ -24,13 +22,6 @@ class MetricsServiceAccessor {
   // disallow instantiation.
   MetricsServiceAccessor() {}
 
-  // Registers/unregisters |observer| to receive MetricsLog notifications
-  // from metrics service.
-  static void AddMetricsServiceObserver(
-      metrics::MetricsServiceObserver* observer);
-  static void RemoveMetricsServiceObserver(
-      metrics::MetricsServiceObserver* observer);
-
   // Registers the specified synthetic field trial (identified by a hash of the
   // trial name and group name) with |metrics_service|, if the service is not
   // NULL, returning true on success.