Remove worker pool names from TaskScheduler.TaskLatency.* histograms.

base/task_scheduler/task_tracker_unittest.cc

Index: base/task_scheduler/task_tracker_unittest.cc
diff --git a/base/task_scheduler/task_tracker_unittest.cc b/base/task_scheduler/task_tracker_unittest.cc
index 161aabb0d7c4c4745f8e9f7674fca7ad1ee60fe4..b4152245b3196d49798ce62490c366271a850824 100644
--- a/base/task_scheduler/task_tracker_unittest.cc
+++ b/base/task_scheduler/task_tracker_unittest.cc
@@ -16,6 +16,9 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
+#include "base/metrics/histogram_base.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/sequence_token.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
@@ -885,5 +888,63 @@ TEST(TaskSchedulerTaskTrackerWaitAllowedTest, WaitAllowed) {
   wait_allowed_test_thread.Join();
 }
 
+// Verify that TaskScheduler.TaskLatency.* histograms are correctly recorded
+// when a task runs.
+TEST(TaskSchedulerTaskTrackerHistogramTest, TaskLatency) {
+  auto statistics_recorder = StatisticsRecorder::CreateTemporaryForTesting();
+
+  TaskTracker tracker;
+
+  struct {
+    const TaskTraits traits;
+    HistogramBase* const expected_histogram;
+  } tests[] = {
+      {TaskTraits().WithPriority(TaskPriority::BACKGROUND),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::BACKGROUND)][0]},
+      {TaskTraits().WithPriority(TaskPriority::BACKGROUND).MayBlock(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::BACKGROUND)][1]},
+      {TaskTraits()
+           .WithPriority(TaskPriority::BACKGROUND)
+           .WithBaseSyncPrimitives(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::BACKGROUND)][1]},
+      {TaskTraits().WithPriority(TaskPriority::USER_VISIBLE),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_VISIBLE)][0]},
+      {TaskTraits().WithPriority(TaskPriority::USER_VISIBLE).MayBlock(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_VISIBLE)][1]},
+      {TaskTraits()
+           .WithPriority(TaskPriority::USER_VISIBLE)
+           .WithBaseSyncPrimitives(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_VISIBLE)][1]},
+      {TaskTraits().WithPriority(TaskPriority::USER_BLOCKING),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_BLOCKING)][0]},
+      {TaskTraits().WithPriority(TaskPriority::USER_BLOCKING).MayBlock(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_BLOCKING)][1]},
+      {TaskTraits()
+           .WithPriority(TaskPriority::USER_BLOCKING)
+           .WithBaseSyncPrimitives(),
+       tracker.task_latency_histograms_[static_cast<int>(
+           TaskPriority::USER_BLOCKING)][1]}};

[gab, 2017/01/05 19:25:46]

Use HistogramTester instead of friending and using the internal value in the
test.

[fdoray, 2017/01/05 20:13:38]

Done.

+
+  for (const auto& test : tests) {

[gab, 2017/01/05 19:25:46]

Interesting use of auto! I thought something was wrong with the above struct as
it doesn't declare a type but I guess auto is fine with that (i.e. auto is the
only valid type here!) :-O

[fdoray, 2017/01/05 20:13:38]

Acknowledged.

+    // Take a snapshot of the histogram so that the snapshot below only contains
+    // increments that occurred within this scope.
+    test.expected_histogram->SnapshotDelta();
+
+    auto task =
+        MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), test.traits, TimeDelta());
+    ASSERT_TRUE(tracker.WillPostTask(task.get()));
+    EXPECT_TRUE(tracker.RunTask(std::move(task), SequenceToken::Create()));
+    EXPECT_EQ(1, test.expected_histogram->SnapshotDelta()->TotalCount());
+  }
+}
+
 }  // namespace internal
 }  // namespace base