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

content/browser/service_worker/service_worker_version.cc

Index: content/browser/service_worker/service_worker_version.cc
diff --git a/content/browser/service_worker/service_worker_version.cc b/content/browser/service_worker/service_worker_version.cc
index 470bc86f5ee2b94066316433b3d34c1670103fe0..f292102e6912f583656c0308ae393ac52e796ec2 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -202,7 +202,8 @@ const int ServiceWorkerVersion::kStopWorkerTimeoutSeconds = 5;
 class ServiceWorkerVersion::Metrics {
  public:
   using EventType = ServiceWorkerMetrics::EventType;
-  explicit Metrics(ServiceWorkerVersion* owner) : owner_(owner) {}
+  explicit Metrics(ServiceWorkerVersion* owner, EventType start_worker_purpose)
+      : owner_(owner), start_worker_purpose_(start_worker_purpose) {}
   ~Metrics() {
     if (owner_->should_exclude_from_uma_)
       return;
@@ -210,6 +211,10 @@ class ServiceWorkerVersion::Metrics {
       ServiceWorkerMetrics::RecordEventHandledRatio(
           ev.first, ev.second.handled_events, ev.second.fired_events);
     }
+    if (ServiceWorkerMetrics::IsNavigationHintEvent(start_worker_purpose_)) {
+      ServiceWorkerMetrics::RecordNavigationHintPrecision(
+          start_worker_purpose_, !event_stats_.empty());
+    }
   }
 
   void RecordEventHandledStatus(EventType event, bool handled) {
@@ -226,6 +231,7 @@ class ServiceWorkerVersion::Metrics {
 
   ServiceWorkerVersion* owner_;
   std::map<EventType, EventStat> event_stats_;
+  const EventType start_worker_purpose_;
 
   DISALLOW_COPY_AND_ASSIGN(Metrics);
 };
@@ -755,7 +761,7 @@ void ServiceWorkerVersion::OnStarted() {
 
   // Fire all start callbacks.
   scoped_refptr<ServiceWorkerVersion> protect(this);
-  RunCallbacks(this, &start_callbacks_, SERVICE_WORKER_OK);
+  RunStartCallbacks(SERVICE_WORKER_OK);
   FOR_EACH_OBSERVER(Listener, listeners_, OnRunningStateChanged(this));
 }
 
@@ -866,8 +872,7 @@ void ServiceWorkerVersion::OnStartSentAndScriptEvaluated(
     ServiceWorkerStatusCode status) {
   if (status != SERVICE_WORKER_OK) {
     scoped_refptr<ServiceWorkerVersion> protect(this);
-    RunCallbacks(this, &start_callbacks_,
-                 DeduceStartWorkerFailureReason(status));
+    RunStartCallbacks(DeduceStartWorkerFailureReason(status));
   }
 }
 
@@ -1301,6 +1306,9 @@ void ServiceWorkerVersion::DidEnsureLiveRegistrationForStartWorker(
             "ServiceWorker", "ServiceWorkerVersion::StartWorker", trace_id,
             "Script", script_url_.spec(), "Purpose",
             ServiceWorkerMetrics::EventTypeToString(purpose));
+        DCHECK(!start_worker_first_purpose_);
+        start_worker_first_purpose_.reset(
+            new ServiceWorkerMetrics::EventType(purpose));
         start_callbacks_.push_back(
             base::Bind(&ServiceWorkerVersion::RecordStartWorkerResult,
                        weak_factory_.GetWeakPtr(), purpose, prestart_status,
@@ -1322,7 +1330,8 @@ void ServiceWorkerVersion::StartWorkerInternal() {
   DCHECK_EQ(STOPPED, running_status());
 
   DCHECK(!metrics_);
-  metrics_.reset(new Metrics(this));
+  DCHECK(start_worker_first_purpose_);
+  metrics_.reset(new Metrics(this, *start_worker_first_purpose_));
 
   StartTimeoutTimer();
 
@@ -1435,7 +1444,7 @@ void ServiceWorkerVersion::OnTimeoutTimer() {
     DCHECK(running_status() == STARTING || running_status() == STOPPING)
         << running_status();
     scoped_refptr<ServiceWorkerVersion> protect(this);
-    RunCallbacks(this, &start_callbacks_, SERVICE_WORKER_ERROR_TIMEOUT);
+    RunStartCallbacks(SERVICE_WORKER_ERROR_TIMEOUT);
     if (running_status() == STARTING)
       embedded_worker_->Stop();
     return;
@@ -1664,9 +1673,8 @@ void ServiceWorkerVersion::OnStoppedInternal(
 
   if (!should_restart) {
     // Let all start callbacks fail.
-    RunCallbacks(this, &start_callbacks_,
-                 DeduceStartWorkerFailureReason(
-                     SERVICE_WORKER_ERROR_START_WORKER_FAILED));
+    RunStartCallbacks(DeduceStartWorkerFailureReason(
+        SERVICE_WORKER_ERROR_START_WORKER_FAILED));
   }
 
   // Let all message callbacks fail (this will also fire and clear all
@@ -1710,4 +1718,9 @@ void ServiceWorkerVersion::OnBeginEvent() {
                                                 idle_time_);
 }
 
+void ServiceWorkerVersion::RunStartCallbacks(ServiceWorkerStatusCode status) {
+  start_worker_first_purpose_.reset();
+  RunCallbacks(this, &start_callbacks_, status);
+}
+
 }  // namespace content