ServiceWorker: Add UMA to measure execution times of oninstall/onfetch

content/browser/service_worker/service_worker_metrics.h

Index: content/browser/service_worker/service_worker_metrics.h
diff --git a/content/browser/service_worker/service_worker_metrics.h b/content/browser/service_worker/service_worker_metrics.h
index deea3b3f1c4758920bde182e05d8aaf5cd806536..4a5a653bdb769b86332b841fe578e20d0e790ae5 100644
--- a/content/browser/service_worker/service_worker_metrics.h
+++ b/content/browser/service_worker/service_worker_metrics.h
@@ -6,6 +6,7 @@
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_METRICS_H_
 
 #include "base/macros.h"
+#include "base/time/time.h"
 #include "content/browser/service_worker/service_worker_database.h"
 
 namespace content {
@@ -39,6 +40,10 @@ class ServiceWorkerMetrics {
   // Counts the number of page loads controlled by a Service Worker.
   static void CountControlledPageLoad();
 
+  // Measure the execution time of onfetch/oninstall event
+  static void MeasureFetchEventExecutionTime(base::TimeDelta delta);
+  static void MeasureRegistrationTime(base::TimeDelta delta);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ServiceWorkerMetrics);
 };