ash:Shelf - Added UMA stats for ShelfAlignment

ash/periodic_metrics_recorder.h

+// Copyright (c) 2013 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 ASH_PERIODIC_METRICS_RECORDER_H_
+#define ASH_PERIODIC_METRICS_RECORDER_H_
+
+#include "base/timer/timer.h"
+
+namespace ash {
+
+class AshPeriodicMetricsRecorder {

[James Cook, 2013/11/01 05:06:28]

Just call it PeriodicMetricsRecorder since it is already in namespace ash. 
Also, it needs a class comment - why does this class exist?  What should the
next programmer add here?

+ public:
+  AshPeriodicMetricsRecorder();
+  ~AshPeriodicMetricsRecorder();
+
+ private:
+  void RecordMetrics();
+
+  base::RepeatingTimer<AshPeriodicMetricsRecorder> timer_;
+};
+
+}  // namespace ash
+
+#endif  // ASH_PERIODIC_METRICS_RECORDER_H_