Speculatively launch Service Workers on mouse/touch events. [4/5]

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 1506fcbb4ad3421cbabcaea7d490571db50eae40..5024f1281f022c29b46f2eabe3dc4f5fb5764f84 100644
--- a/content/browser/service_worker/service_worker_metrics.h
+++ b/content/browser/service_worker/service_worker_metrics.h
@@ -136,6 +136,9 @@ class ServiceWorkerMetrics {
   // Converts an event type to a string. Used for tracing.
   static const char* EventTypeToString(EventType event_type);
 
+  // Returns true when the event is for a navigation hint.
+  static bool IsNavigationHintEvent(EventType event_type);
+
   // Excludes NTP scope from UMA for now as it tends to dominate the stats and
   // makes the results largely skewed. Some metrics don't follow this policy
   // and hence don't call this function.
@@ -198,6 +201,13 @@ class ServiceWorkerMetrics {
                                       size_t handled_events,
                                       size_t fired_events);
 
+  // Records the precision of the speculative launch of Service Workers for
+  // each navigation hint type when the worker is stopped. If there was no
+  // event fetched to the worker, |event_fired| is false. This means that the

[nhiroki, 2016/07/28 05:38:37]

fetched to -> fired on?

[horo, 2016/07/28 08:15:48]

Done.

+  // speculative launch was meaningless.

[nhiroki, 2016/07/28 05:38:37]

'meaningless' sounds somewhat negative. How about 'wasn't helpful'?

[horo, 2016/07/28 08:15:48]

Done.

+  static void RecordNavigationHintPrecision(EventType start_worker_purpose,
+                                            bool event_fired);
+
   // Records how often a dispatched event times out.
   static void RecordEventTimeout(EventType event);