Report the duration of sampled tasks with histogram.

components/scheduler/renderer/task_time_reporter.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/task_time_reporter.h"
+
+#include "base/metrics/histogram_macros.h"
+
+namespace scheduler {
+TaskTimeReporter::TaskTimeReporter() {}
+
+TaskTimeReporter::~TaskTimeReporter() {}
+
+void TaskTimeReporter::ReportTaskTime(base::TimeDelta duration) {
+  UMA_HISTOGRAM_CUSTOM_COUNTS("RendererScheduler.TaskTime",
+                              duration.InMicroseconds(), 1, 1000000, 50);

[Ilya Sherman, 2016/08/03 00:54:46]

Optional nit: It seems rather heavy-weight to define an entire class for this
one macro call.

[Sami, 2016/08/03 10:01:22]

I agree -- could you move the macro to the call site?

+}
+}