Introduce ServiceWorker.ActivatedWorkerPreparationForMainFrame.Time UMA.

content/browser/service_worker/service_worker_url_request_job.cc

Index: content/browser/service_worker/service_worker_url_request_job.cc
diff --git a/content/browser/service_worker/service_worker_url_request_job.cc b/content/browser/service_worker/service_worker_url_request_job.cc
index e06e5935e242c6eada3978d177e1aeeb823458eb..c117b43fe65e1d78d487d3e65e4dcfdfc165529f 100644
--- a/content/browser/service_worker/service_worker_url_request_job.cc
+++ b/content/browser/service_worker/service_worker_url_request_job.cc
@@ -22,6 +22,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "content/browser/resource_context_impl.h"
+#include "content/browser/service_worker/embedded_worker_instance.h"
 #include "content/browser/service_worker/service_worker_fetch_dispatcher.h"
 #include "content/browser/service_worker/service_worker_provider_host.h"
 #include "content/browser/service_worker/service_worker_response_info.h"
@@ -632,9 +633,34 @@ void ServiceWorkerURLRequestJob::CreateRequestBodyBlob(std::string* blob_uuid,
   *blob_size = total_size;
 }
 
-void ServiceWorkerURLRequestJob::DidPrepareFetchEvent() {
+void ServiceWorkerURLRequestJob::DidPrepareFetchEvent(
+    scoped_refptr<ServiceWorkerVersion> version) {
   worker_ready_time_ = base::TimeTicks::Now();
   load_timing_info_.send_start = worker_ready_time_;
+
+  // Record the time taken to find a Service Worker registration and wait for a
+  // worker started to send a FetchEvent request for a main frame resource. The
+  // measurement starts when the browser process recieves the request and ends
+  // when it finds a running worker or it successfully starts a worker. We
+  // don't record it in the following situations:
+  // 1) The worker was not activated yet. This is intended to avoid including
+  //    the time for the activation.
+  // 2) The worker was started for the fetch AND DevTools was attached during
+  //    startup. This is intended to avoid including the time for debugging.
+  // 3) The request is for New Tab Page.
+  if (resource_type_ != RESOURCE_TYPE_MAIN_FRAME)
+    return;
+  if (worker_already_activated_)
+    return;
+  if (version->skip_recording_startup_time() &&
+      initial_worker_status_ != EmbeddedWorkerStatus::RUNNING) {
+    return;
+  }
+  if (ServiceWorkerMetrics::ShouldExcludeURLFromHistogram(request()->url()))
+    return;
+  ServiceWorkerMetrics::RecordActivatedWorkerPreparationTimeForMainFrame(
+      worker_ready_time_ - request()->creation_time(), initial_worker_status_,
+      version->embedded_worker()->start_situation());
 }
 
 void ServiceWorkerURLRequestJob::DidDispatchFetchEvent(
@@ -962,11 +988,15 @@ void ServiceWorkerURLRequestJob::RequestBodyBlobsCompleted(bool success) {
     return;
   }
 
+  worker_already_activated_ =
+      active_worker->status() == ServiceWorkerVersion::ACTIVATED;
+  initial_worker_status_ = active_worker->running_status();
+
   DCHECK(!fetch_dispatcher_);
   fetch_dispatcher_.reset(new ServiceWorkerFetchDispatcher(
       CreateFetchRequest(), active_worker, resource_type_,
       base::Bind(&ServiceWorkerURLRequestJob::DidPrepareFetchEvent,
-                 weak_factory_.GetWeakPtr()),
+                 weak_factory_.GetWeakPtr(), active_worker),
       base::Bind(&ServiceWorkerURLRequestJob::DidDispatchFetchEvent,
                  weak_factory_.GetWeakPtr())));
   worker_start_time_ = base::TimeTicks::Now();