Report expected task queueing time via UMA

components/scheduler/renderer/coarse_duration_timer.h

+// 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 COMPONENTS_SCHEDULER_RENDERER_COARSE_DURATION_TIMER_H_
+#define COMPONENTS_SCHEDULER_RENDERER_COARSE_DURATION_TIMER_H_
+
+#include "base/message_loop/message_loop.h"
+#include "base/optional.h"
+#include "base/time/time.h"
+
+namespace scheduler {
+
+// TODO - add locking things.

[tdresser, 2016/05/30 19:07:46]

^

+class CoarseDurationTimer : public base::MessageLoop::RecentTimeObserver {
+ public:
+  // RecentTimeObserver implementation:
+  void OnUpdateRecentTime(base::TimeTicks time) override;
+
+  void BeginInterval();
+  base::TimeDelta EndInterval();
+  base::TimeTicks most_recent_time() { return most_recent_time_; }
+
+ private:
+  enum class State {
+    OUTSIDE_INTERVAL,
+    WITHIN_INTERVAL_NEEDS_START,
+    WITHIN_INTERVAL
+  };
+
+  State state_;
+  base::TimeTicks start_time_;
+  base::TimeTicks most_recent_time_;
+};
+
+}  // namespace scheduler
+
+#endif  // COMPONENTS_SCHEDULER_RENDERER_COARSE_DURATION_TIMER_H_