Report expected task queueing time via UMA

components/scheduler/base/task_time_tracker.h

Index: components/scheduler/base/task_time_tracker.h
diff --git a/components/scheduler/base/task_time_tracker.h b/components/scheduler/base/task_time_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..7328f89d6a01aea8a077c28eefa80b0484555317
--- /dev/null
+++ b/components/scheduler/base/task_time_tracker.h
@@ -0,0 +1,47 @@
+// Copyright 2016 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.
+
+#ifndef CONTENT_RENDERER_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+#define CONTENT_RENDERER_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/time/default_tick_clock.h"
+#include "base/time/time.h"
+#include "components/scheduler/base/queueing_time_estimator.h"
+#include "components/scheduler/scheduler_export.h"
+
+namespace base {
+class TickClock;

[Sami, 2016/07/05 14:40:39]

Unused?

[tdresser, 2016/07/05 15:52:20]

Done.

+}
+
+namespace scheduler {
+
+class SCHEDULER_EXPORT TaskTimeTracker : public QueueingTimeEstimator::Client {

[Sami, 2016/07/05 14:40:39]

I'm wondering if this should just be a virtual interface with just
ReportTaskTime? That way the RendererScheduler could implement that interface,
pipe the data into a QueueingTimeEstimator member and use the result as it
wanted.

[alex clarke (OOO till 29th), 2016/07/05 14:59:35]

+1 we'd like to use the timings for other purposes (e.g. throttling).

I don't mind if the TQM or the Scheduler owns the TaskTimeTracker (the latter
might be nice since we don't need it for workers). You might consider adding a
setter method on the TQM (plumbed through the helper).

[tdresser, 2016/07/05 20:09:38]

Done.

+ public:
+  class TaskTimeObserver {
+   public:
+    virtual void OnQueueingTimeForWindowEstimated(
+        base::TimeDelta queueing_time) = 0;
+    virtual ~TaskTimeObserver() {}
+  };
+
+  TaskTimeTracker();
+  ~TaskTimeTracker() override;
+
+  void ReportTaskTime(base::TimeTicks startTime, base::TimeTicks endTime);
+  void SetObserver(TaskTimeObserver*);
+
+  // QueueingTimeEstimator::Client implementation:
+  void OnQueueingTimeForWindowEstimated(base::TimeDelta queueing_time) override;
+
+  TaskTimeObserver* task_time_observer_;  // Not Owned

[Sami, 2016/07/05 14:40:39]

Did you mean to make these private? This observer also seems unused.

[tdresser, 2016/07/05 15:52:20]

Yeah, they're private in the next patch.

Removed observer.

+  QueueingTimeEstimator queueing_time_estimator_;
+}; // scheduler

[alex clarke (OOO till 29th), 2016/07/05 13:47:45]

nit: DISALLOW_COPY_AND_ASSIGN

[tdresser, 2016/07/05 14:30:13]

Eeep - and also add "private".

Done.

+
+#endif // CONTENT_RENDERER_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+
+}

[Sami, 2016/07/05 14:40:39]

This brace seems misplaced.

[tdresser, 2016/07/05 20:09:38]

Done.