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

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 5095b53b9877f5d8cb2e2fb7e6f63995efc3db61..d4bc6e94488bddc455d201a927bb72e2397a577a 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -66,6 +66,12 @@ std::string EventTypeToSuffix(ServiceWorkerMetrics::EventType event_type) {
       return "_UNKNOWN";
     case ServiceWorkerMetrics::EventType::FOREIGN_FETCH:
       return "_FOREIGN_FETCH";
+    case ServiceWorkerMetrics::EventType::NAVIGATION_HINT_LINK_MOUSE_DOWN:
+      return "_NAVIGATION_HINT_LINK_MOUSE_DOWN";
+    case ServiceWorkerMetrics::EventType::NAVIGATION_HINT_LINK_TAP_UNCONFIRMED:
+      return "_NAVIGATION_HINT_LINK_TAP_UNCONFIRMED";
+    case ServiceWorkerMetrics::EventType::NAVIGATION_HINT_LINK_TAP_DOWN:
+      return "_NAVIGATION_HINT_LINK_TAP_DOWN";
     case ServiceWorkerMetrics::EventType::NUM_TYPES:
       NOTREACHED() << static_cast<int>(event_type);
   }
@@ -158,6 +164,12 @@ const char* ServiceWorkerMetrics::EventTypeToString(EventType event_type) {
       return "Unknown";
     case EventType::FOREIGN_FETCH:
       return "Foreign Fetch";
+    case EventType::NAVIGATION_HINT_LINK_MOUSE_DOWN:
+      return "Navigation Hint Link Mouse Down";
+    case EventType::NAVIGATION_HINT_LINK_TAP_UNCONFIRMED:
+      return "Navigation Hint Link Tap Unconfiemed";
+    case EventType::NAVIGATION_HINT_LINK_TAP_DOWN:
+      return "Navigation Hint Link Tap Down";
     case EventType::NUM_TYPES:
       break;
   }
@@ -165,6 +177,12 @@ const char* ServiceWorkerMetrics::EventTypeToString(EventType event_type) {
   return "error";
 }
 
+bool ServiceWorkerMetrics::IsNavigationHintEvent(EventType event_type) {
+  return event_type == EventType::NAVIGATION_HINT_LINK_MOUSE_DOWN ||
+         event_type == EventType::NAVIGATION_HINT_LINK_TAP_UNCONFIRMED ||
+         event_type == EventType::NAVIGATION_HINT_LINK_TAP_DOWN;
+}
+
 bool ServiceWorkerMetrics::ShouldExcludeSiteFromHistogram(Site site) {
   return site == ServiceWorkerMetrics::Site::NEW_TAB_PAGE;
 }
@@ -349,6 +367,30 @@ void ServiceWorkerMetrics::RecordEventHandledRatio(EventType event,
   }
 }
 
+void ServiceWorkerMetrics::RecordNavigationHintPrecision(
+    EventType start_worker_purpose,
+    bool event_fired) {
+  UMA_HISTOGRAM_BOOLEAN("ServiceWorker.NavigationHintPrecision", event_fired);
+  switch (start_worker_purpose) {
+    case EventType::NAVIGATION_HINT_LINK_MOUSE_DOWN:
+      UMA_HISTOGRAM_BOOLEAN(
+          "ServiceWorker.NavigationHintPrecision.LINK_MOUSE_DOWN", event_fired);
+      break;
+    case EventType::NAVIGATION_HINT_LINK_TAP_UNCONFIRMED:
+      UMA_HISTOGRAM_BOOLEAN(
+          "ServiceWorker.NavigationHintPrecision.LINK_TAP_UNCONFIRMED",
+          event_fired);
+      break;
+    case EventType::NAVIGATION_HINT_LINK_TAP_DOWN:
+      UMA_HISTOGRAM_BOOLEAN(
+          "ServiceWorker.NavigationHintPrecision.LINK_TAP_DOWN", event_fired);
+      break;
+    default:
+      // Do nothing.
+      break;
+  }
+}
+
 void ServiceWorkerMetrics::RecordEventTimeout(EventType event) {
   UMA_HISTOGRAM_ENUMERATION("ServiceWorker.RequestTimeouts.Count",
                             static_cast<int>(event),
@@ -405,6 +447,10 @@ void ServiceWorkerMetrics::RecordEventDuration(EventType event,
       UMA_HISTOGRAM_MEDIUM_TIMES("ServiceWorker.ExtendableMessageEvent.Time",
                                  time);
       break;
+    // Those navigation hints should not be sent as request events.
+    case EventType::NAVIGATION_HINT_LINK_MOUSE_DOWN:
+    case EventType::NAVIGATION_HINT_LINK_TAP_UNCONFIRMED:
+    case EventType::NAVIGATION_HINT_LINK_TAP_DOWN:
 
     case EventType::UNKNOWN:
     case EventType::NUM_TYPES: