Add UMA for service worker navigation preload.

content/browser/service_worker/service_worker_metrics_unittest.cc

Index: content/browser/service_worker/service_worker_metrics_unittest.cc
diff --git a/content/browser/service_worker/service_worker_metrics_unittest.cc b/content/browser/service_worker/service_worker_metrics_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3348d6c28ec19e8891cf2c6b6ad03f3e67e55bb8
--- /dev/null
+++ b/content/browser/service_worker/service_worker_metrics_unittest.cc
@@ -0,0 +1,106 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/service_worker/service_worker_metrics.h"
+
+#include "base/test/histogram_tester.h"
+#include "content/browser/service_worker/embedded_worker_status.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+namespace {
+const std::string kNavigationPreloadSuffix = "_NavigationPreloadEnabled";
+const std::string kStartWorkerDuringStartupSuffix = "_StartWorkerDuringStartup";
+const std::string kStartWorkerExistingProcessSuffix =
+    "_StartWorkerExistingProcess";
+const std::string kPreparationTime =
+    "ServiceWorker.ActivatedWorkerPreparationForMainFrame.Time";
+const std::string kPreparationType =
+    "ServiceWorker.ActivatedWorkerPreparationForMainFrame.Type";
+}  // namespace
+
+TEST(ServiceWorkerMetricsTest, ActivatedWorkerPreparation) {
+  base::TimeDelta time = base::TimeDelta::FromMilliseconds(123);
+  {
+    // Test preparation when the worker was STARTING.
+    base::HistogramTester histogram_tester;
+    ServiceWorkerMetrics::RecordActivatedWorkerPreparationForMainFrame(
+        time, EmbeddedWorkerStatus::STARTING,
+        ServiceWorkerMetrics::StartSituation::UNKNOWN,
+        false /* did_navigation_preload */);
+    histogram_tester.ExpectUniqueSample(
+        kPreparationType,
+        static_cast<int>(ServiceWorkerMetrics::WorkerPreparationType::STARTING),
+        1);
+    histogram_tester.ExpectTotalCount(
+        kPreparationType + kNavigationPreloadSuffix, 0);
+    histogram_tester.ExpectTimeBucketCount(kPreparationTime, time, 1);
+    histogram_tester.ExpectTimeBucketCount(kPreparationTime + "_StartingWorker",
+                                           time, 1);
+    histogram_tester.ExpectTotalCount(
+        kPreparationTime + kNavigationPreloadSuffix, 0);
+  }
+
+  {
+    // Test preparation when the worker started up during startup.
+    base::HistogramTester histogram_tester;
+    ServiceWorkerMetrics::RecordActivatedWorkerPreparationForMainFrame(
+        time, EmbeddedWorkerStatus::STOPPED,
+        ServiceWorkerMetrics::StartSituation::DURING_STARTUP,
+        true /* did_navigation_preload */);
+    histogram_tester.ExpectUniqueSample(
+        kPreparationType,
+        static_cast<int>(
+            ServiceWorkerMetrics::WorkerPreparationType::START_DURING_STARTUP),
+        1);
+    histogram_tester.ExpectUniqueSample(
+        kPreparationType + kNavigationPreloadSuffix,
+        static_cast<int>(
+            ServiceWorkerMetrics::WorkerPreparationType::START_DURING_STARTUP),
+        1);
+    histogram_tester.ExpectTimeBucketCount(kPreparationTime, time, 1);
+    histogram_tester.ExpectTimeBucketCount(
+        kPreparationTime + kNavigationPreloadSuffix, time, 1);
+    // This would be the correct name for such a histogram, but it's
+    // intentionally not logged (see comment in
+    // RecordActivatedWorkerPreparationForMainFrame), so expect zero count.
+    histogram_tester.ExpectTotalCount(kPreparationTime +
+                                          kStartWorkerDuringStartupSuffix +
+                                          kNavigationPreloadSuffix,
+                                      0);
+    histogram_tester.ExpectTotalCount(kPreparationTime +
+                                          kStartWorkerExistingProcessSuffix +
+                                          kNavigationPreloadSuffix,
+                                      0);
+  }
+
+  {
+    // Test preparation when the worker started up in an existing process.
+    base::HistogramTester histogram_tester;
+    ServiceWorkerMetrics::RecordActivatedWorkerPreparationForMainFrame(
+        time, EmbeddedWorkerStatus::STOPPED,
+        ServiceWorkerMetrics::StartSituation::EXISTING_PROCESS,
+        true /* did_navigation_preload */);
+    histogram_tester.ExpectUniqueSample(
+        kPreparationType,
+        static_cast<int>(ServiceWorkerMetrics::WorkerPreparationType::
+                             START_IN_EXISTING_PROCESS),
+        1);
+    histogram_tester.ExpectUniqueSample(
+        kPreparationType + kNavigationPreloadSuffix,
+        static_cast<int>(ServiceWorkerMetrics::WorkerPreparationType::
+                             START_IN_EXISTING_PROCESS),
+        1);
+    histogram_tester.ExpectTimeBucketCount(kPreparationTime, time, 1);
+    histogram_tester.ExpectTimeBucketCount(
+        kPreparationTime + kNavigationPreloadSuffix, time, 1);
+    histogram_tester.ExpectTimeBucketCount(
+        kPreparationTime + kStartWorkerExistingProcessSuffix +
+            kNavigationPreloadSuffix,
+        time, 1);
+  }
+}
+
+}  // namespace content