Refactor HashedExtensionMetrics into ExtensionsMetricsProvider.

chrome/browser/metrics/metrics_services_manager.cc

Index: chrome/browser/metrics/metrics_services_manager.cc
diff --git a/chrome/browser/metrics/metrics_services_manager.cc b/chrome/browser/metrics/metrics_services_manager.cc
index 4c7fbe0fef527d73ac8928ea79d9dbce22c93d86..0b5a278c58d0d575d5a8191d95b55e5e8563c0ef 100644
--- a/chrome/browser/metrics/metrics_services_manager.cc
+++ b/chrome/browser/metrics/metrics_services_manager.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/metrics/metrics_services_manager.h"
 
+#include "chrome/browser/metrics/extensions_metrics_provider.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/metrics/metrics_state_manager.h"
 #include "chrome/browser/metrics/variations/variations_service.h"
@@ -22,6 +23,9 @@ MetricsService* MetricsServicesManager::GetMetricsService() {
   if (!metrics_service_) {
     metrics_service_.reset(
       new MetricsService(GetMetricsStateManager(), &metrics_service_client_));
+    metrics_service_->RegisterMetricsProvider(
+        scoped_ptr<metrics::MetricsProvider>(
+            new ExtensionsMetricsProvider(GetMetricsStateManager())));
   }
   return metrics_service_.get();
 }