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

base/task_scheduler/task_tracker.h

Index: base/task_scheduler/task_tracker.h
diff --git a/base/task_scheduler/task_tracker.h b/base/task_scheduler/task_tracker.h
index a5caf213985ea20bd986cafb70bea32d76891207..26ed110cbd9bf6a60da74114fd98e9c8b8722b89 100644
--- a/base/task_scheduler/task_tracker.h
+++ b/base/task_scheduler/task_tracker.h
@@ -10,6 +10,7 @@
 #include "base/atomicops.h"
 #include "base/base_export.h"
 #include "base/callback_forward.h"
+#include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_base.h"
 #include "base/synchronization/waitable_event.h"
@@ -21,13 +22,15 @@
 namespace base {
 
 class ConditionVariable;
+class HistogramBase;
 class SequenceToken;
 
 namespace internal {
 
 // All tasks go through the scheduler's TaskTracker when they are posted and
-// when they are executed. The TaskTracker enforces shutdown semantics and takes
-// care of tracing and profiling. This class is thread-safe.
+// when they are executed. The TaskTracker sets up the environment to run tasks,
+// enforces shutdown semantics, records metrics and takes care of tracing and

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

, and

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

Done.

+// profiling. This class is thread-safe.
 class BASE_EXPORT TaskTracker {
  public:
   TaskTracker();
@@ -79,6 +82,8 @@ class BASE_EXPORT TaskTracker {
   virtual void PerformRunTask(std::unique_ptr<Task> task);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(TaskSchedulerTaskTrackerHistogramTest, TaskLatency);
+
   class State;
 
   void PerformShutdown();
@@ -106,6 +111,10 @@ class BASE_EXPORT TaskTracker {
   // it reaches zero.
   void DecrementNumPendingUndelayedTasks();
 
+  // Records the TaskScheduler.TaskLatency.[task priority].[may block] histogram
+  // for |task|.
+  void RecordTaskLatencyHistogram(Task* task);
+
   // Number of tasks blocking shutdown and boolean indicating whether shutdown
   // has started.
   const std::unique_ptr<State> state_;
@@ -133,6 +142,12 @@ class BASE_EXPORT TaskTracker {
   // completes.
   std::unique_ptr<WaitableEvent> shutdown_event_;
 
+  // TaskScheduler.TaskLatency.[task priority].[may block] histograms. The first
+  // index is a TaskPriority. The second index is 0 for non-blocking tasks, 1
+  // for blocking tasks. Intentionally leaked.
+  HistogramBase* const
+      task_latency_histograms_[static_cast<int>(TaskPriority::HIGHEST) + 1][2];
+
   // Number of BLOCK_SHUTDOWN tasks posted during shutdown.
   HistogramBase::Sample num_block_shutdown_tasks_posted_during_shutdown_ = 0;