[Night Light] CL4: Automatic schedule backend.

ash/system/night_light/time_of_day.h

Index: ash/system/night_light/time_of_day.h
diff --git a/ash/system/night_light/time_of_day.h b/ash/system/night_light/time_of_day.h
new file mode 100644
index 0000000000000000000000000000000000000000..b270b8f5b9e05c98f48f5791ae81712eb6590d7c
--- /dev/null
+++ b/ash/system/night_light/time_of_day.h
@@ -0,0 +1,52 @@
+// Copyright 2017 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_SYSTEM_NIGHT_LIGHT_TIME_OF_DAY_H_
+#define ASH_SYSTEM_NIGHT_LIGHT_TIME_OF_DAY_H_
+
+#include <string>
+
+#include "ash/ash_export.h"
+#include "base/time/time.h"
+
+namespace ash {
+
+// Represents the time of the day as a simple number of minutes since 00:00
+// regardless of the date or the timezone. This makes it simple to persist this
+// as an integer user pref.
+class ASH_EXPORT TimeOfDay {
+ public:
+  // |offset_minutes| is the number of minutes since 00:00. If |offset_minutes|
+  // is equal to the offset minutes in 24 hours, it will be reset to 0 to
+  // represent the time 00:00 (12:00 AM). Offsets greater than the minutes in
+  // 24 hours are not allowed.
+  explicit TimeOfDay(int offset_minutes);
+  TimeOfDay(const TimeOfDay& other) = default;
+  TimeOfDay& operator=(const TimeOfDay& rhs) = default;
+  ~TimeOfDay() = default;
+
+  // Converts to a minutes offset representation from |time| dropping the
+  // seconds and milliseconds.
+  static TimeOfDay FromTime(const base::Time& time);
+
+  bool operator==(const TimeOfDay& rhs) const;
+
+  int offset_minutes_from_zero_hour() const {
+    return offset_minutes_from_zero_hour_;
+  }
+
+  // Converts to an actual point in time today. If this fail for some reason,
+  // the NULL time will be returned.

[James Cook, 2017/05/24 15:42:47]

nit: "NULL time" seems weird. Maybe Time() or "epoch".

[afakhry, 2017/05/24 16:25:35]

Done.

+  base::Time ToTimeToday() const;
+
+  // Converts to a string in the format "3:07 PM".
+  std::string ToString() const;
+
+ private:
+  int offset_minutes_from_zero_hour_;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_NIGHT_LIGHT_TIME_OF_DAY_H_