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..11522bd3324e680dff54bd659127ec6f12402fed 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
+  // main/sub frame fetch event fired on the worker, |frame_fetch_event_fired|
+  // is false. This means that the speculative launch wasn't helpful.
+  static void RecordNavigationHintPrecision(EventType start_worker_purpose,
+                                            bool frame_fetch_event_fired);
+
   // Records how often a dispatched event times out.
   static void RecordEventTimeout(EventType event);