Add UMA for how long service workers run for.

content/browser/service_worker/service_worker_lifetime_tracker_unittest.cc

+// 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_lifetime_tracker.h"
+
+#include "base/test/histogram_tester.h"
+#include "base/test/simple_test_tick_clock.h"
+#include "base/time/tick_clock.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "content/public/test/test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+class ServiceWorkerLifetimeTrackerTest : public testing::Test {
+ public:
+  ServiceWorkerLifetimeTrackerTest()
+      : tick_clock_(new base::SimpleTestTickClock()),
+        tracker_(base::WrapUnique(tick_clock_)) {}
+
+  base::SimpleTestTickClock* tick_clock() { return tick_clock_; }
+  ServiceWorkerLifetimeTracker* tracker() { return &tracker_; }
+
+  void AdvanceAndRunTimer(bool expect_running) {
+    // Advance to the scheduled time and run the timer task.
+    tick_clock()->SetNowTicks(tracker()->timer_.desired_run_time());
+    tracker()->timer_.user_task().Run();
+
+    // The timer's desired run time is still unchanged here. So reset it if the
+    // timer is still running.
+    if (expect_running) {
+      EXPECT_TRUE(tracker()->timer_.IsRunning());
+      tracker()->timer_.Reset();
+    } else {
+      EXPECT_FALSE(tracker()->timer_.IsRunning());
+    }
+  }
+
+ private:
+  TestBrowserThreadBundle thread_bundle_;
+
+  // Not owned.
+  base::SimpleTestTickClock* tick_clock_;
+
+  ServiceWorkerLifetimeTracker tracker_;
+};
+
+TEST_F(ServiceWorkerLifetimeTrackerTest, Metrics) {
+  int64_t kVersion1 = 13;  // dummy value
+  int64_t kVersion2 = 14;  // dummy value
+
+  tick_clock()->SetNowTicks(base::TimeTicks::Now());
+
+  // Start a worker to kick off the timer.
+  tracker()->StartTiming(kVersion2);
+
+  // Run a worker for 10 seconds.
+  {
+    base::HistogramTester metrics;
+    tracker()->StartTiming(kVersion1);
+    tick_clock()->Advance(base::TimeDelta::FromSeconds(10));
+    tracker()->StopTiming(kVersion1);
+    metrics.ExpectTimeBucketCount("ServiceWorker.Runtime",
+                                  base::TimeDelta::FromSeconds(10), 1);
+  }
+
+  // Advance to the 5 minute mark and run the timer. It should not record
+  // StillRunning.
+  {
+    base::HistogramTester metrics;
+    AdvanceAndRunTimer(true /* expect_running */);
+    metrics.ExpectTotalCount("ServiceWorker.StillRunningTime", 0);
+  }
+
+  // Advance again. It should record StillRunning.
+  {
+    base::HistogramTester metrics;
+    AdvanceAndRunTimer(true /* expect_running */);
+    metrics.ExpectTimeBucketCount("ServiceWorker.StillRunningTime",
+                                  base::TimeDelta::FromMinutes(10), 1);
+  }
+
+  // Advance 30 seconds and stop the worker. It should record Runtime.
+  {
+    base::HistogramTester metrics;
+    tick_clock()->Advance(base::TimeDelta::FromSeconds(30));
+    tracker()->StopTiming(kVersion2);
+    metrics.ExpectTimeBucketCount(
+        "ServiceWorker.Runtime",
+        base::TimeDelta::FromMinutes(10) + base::TimeDelta::FromSeconds(30), 1);
+  }
+
+  {
+    base::HistogramTester metrics;
+    // Start a worker and abort the timing.
+    tracker()->StartTiming(kVersion1);
+    tick_clock()->Advance(base::TimeDelta::FromSeconds(10));
+    tracker()->AbortTiming(kVersion1);
+
+    // Advance to the next 5 minute mark. It should not record another
+    // StillRunning.
+    AdvanceAndRunTimer(false /* expect_running */);
+
+    // Aborting multiple times should be fine.
+    tracker()->AbortTiming(kVersion1);
+    tracker()->AbortTiming(kVersion1);
+    // StopTiming should not record another StillRunning.
+    tracker()->StopTiming(kVersion1);
+
+    metrics.ExpectTotalCount("ServiceWorker.StillRunningTime", 0);
+    metrics.ExpectTotalCount("ServiceWorker.Runtime", 0);
+  }
+}
+
+}  // namespace content