Introduce ServiceWorker.ActivatedWorkerPreparationForMainFrame.Time UMA.

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..eaf8071ffa4f87e00f6e4352b14509e80400d36f 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -10,6 +10,7 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_util.h"
+#include "content/browser/service_worker/embedded_worker_status.h"
 #include "content/common/service_worker/service_worker_types.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
@@ -72,6 +73,33 @@ std::string EventTypeToSuffix(ServiceWorkerMetrics::EventType event_type) {
   return "_UNKNOWN";
 }
 
+std::string GetWorkerPreparationSuffix(
+    EmbeddedWorkerStatus initial_worker_status,
+    ServiceWorkerMetrics::StartSituation start_situation) {
+  switch (initial_worker_status) {
+    case EmbeddedWorkerStatus::STOPPED: {
+      switch (start_situation) {
+        case ServiceWorkerMetrics::StartSituation::DURING_STARTUP:
+          return "_StartWorkerDuringStartup";
+        case ServiceWorkerMetrics::StartSituation::NEW_PROCESS:
+          return "_StartWorkerNewProcess";
+        case ServiceWorkerMetrics::StartSituation::EXISTING_PROCESS:
+          return "_StartWorkerExistingProcess";
+        default:
+          NOTREACHED() << static_cast<int>(start_situation);
+      }
+    }
+    case EmbeddedWorkerStatus::STARTING:
+      return "_StartingWorker";
+    case EmbeddedWorkerStatus::RUNNING:
+      return "_RunningWorker";
+    case EmbeddedWorkerStatus::STOPPING:
+      return "_StoppingWorker";
+  }
+  NOTREACHED();
+  return "_UNKNOWN";
+}
+
 // Use this for histograms with dynamically generated names, which
 // otherwise can't use the UMA_HISTOGRAM macro without code duplication.
 void RecordSuffixedTimeHistogram(const std::string& name,
@@ -288,6 +316,18 @@ void ServiceWorkerMetrics::RecordStartWorkerTime(base::TimeDelta time,
   }
 }
 
+void ServiceWorkerMetrics::RecordActivatedWorkerPreparationTimeForMainFrame(
+    base::TimeDelta time,
+    EmbeddedWorkerStatus initial_worker_status,
+    StartSituation start_situation) {
+  std::string name =
+      "ServiceWorker.ActivatedWorkerPreparationForMainFrame.Time";
+  UMA_HISTOGRAM_MEDIUM_TIMES(name, time);
+  RecordSuffixedTimeHistogram(
+      name, GetWorkerPreparationSuffix(initial_worker_status, start_situation),
+      time);
+}
+
 void ServiceWorkerMetrics::RecordWorkerStopped(StopStatus status) {
   UMA_HISTOGRAM_ENUMERATION("ServiceWorker.WorkerStopped",
                             static_cast<int>(status),