ServiceWorker: Record result of purging stale resources

content/browser/service_worker/service_worker_metrics.cc

Index: content/browser/service_worker/service_worker_metrics.cc
diff --git a/content/browser/service_worker/service_worker_metrics.cc b/content/browser/service_worker/service_worker_metrics.cc
index ad1c1c4a367f5b7a47688f8a1c1e9ffd2288b427..5843c84ccc045acba3209048ce590da62668ead7 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -5,6 +5,7 @@
 #include "content/browser/service_worker/service_worker_metrics.h"
 
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/metrics/user_metrics_action.h"
 #include "base/strings/string_util.h"
 #include "content/public/browser/browser_thread.h"
@@ -83,6 +84,11 @@ void ServiceWorkerMetrics::RecordDestroyDatabaseResult(
                             status, ServiceWorkerDatabase::STATUS_ERROR_MAX);
 }
 
+void ServiceWorkerMetrics::RecordPurgeResourceResult(int net_error) {
+  UMA_HISTOGRAM_SPARSE_SLOWLY("ServiceWorker.Storage.PurgeResourceResult",
+                              net_error);

[Alexei Svitkine (slow), 2015/07/17 15:08:52]

I think net errors are negative, so you have to negate it here, e.g. see:

https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/met...

[nhiroki, 2015/07/21 02:27:23]

Good catch! Done.

+}
+
 void ServiceWorkerMetrics::RecordDiskCacheMigrationResult(
     DiskCacheMigrationResult result) {
   UMA_HISTOGRAM_ENUMERATION("ServiceWorker.Storage.DiskCacheMigrationResult",