Report expected task queueing time via UMA

components/scheduler/renderer/coarse_duration_timer.cc

+// 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.
+
+#include "components/scheduler/renderer/coarse_duration_timer.h"
+
+#include "base/message_loop/message_loop.h"
+
+namespace scheduler {
+
+void CoarseDurationTimer::OnUpdateRecentTime(base::TimeTicks recent_time) {
+  most_recent_time_ = recent_time;
+  if (state_ == State::WITHIN_INTERVAL_NEEDS_START) {
+    start_time_ = recent_time;
+    state_ = State::WITHIN_INTERVAL;
+  }
+}
+
+void CoarseDurationTimer::BeginInterval() {
+  //  DCHECK(state_ == State::OUTSIDE_INTERVAL);
+  state_ = State::WITHIN_INTERVAL_NEEDS_START;
+}
+
+base::TimeDelta CoarseDurationTimer::EndInterval() {
+  base::TimeDelta duration;
+  //  DCHECK(state_ != State::OUTSIDE_INTERVAL);
+
+  // If we haven't received a single time update within this interval, report
+  // a duration of 0.
+  if (state_ != State::WITHIN_INTERVAL_NEEDS_START)
+    duration = most_recent_time_ - start_time_;
+  state_ = State::OUTSIDE_INTERVAL;
+
+  if (!duration.is_zero())
+    LOG(ERROR) << "DURATION IS " << duration.InMillisecondsF();
+  return duration;
+}
+
+}  // namespace scheduler