Migrates battery_status from content/renderer/ to WebKit/platform/

third_party/WebKit/Source/platform/battery/BatteryStatus.h

+// Copyright 2014 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 BatteryStatus_h
+#define BatteryStatus_h
+
+#include "wtf/Assertions.h"
+
+#include <cmath>
+#include <limits>
+
+namespace blink {
+
+// Simple struct to hold the battery status. This class is copyable.
+class BatteryStatus final {
+public:
+    BatteryStatus()
+        : m_charging(true)
+        , m_chargingTime(0)
+        , m_dischargingTime(std::numeric_limits<double>::infinity())
+        , m_level(1) { }
+    BatteryStatus(bool charging, double chargingTime, double dischargingTime, double level)
+        : m_charging(charging)
+        , m_chargingTime(chargingTime)
+        , m_dischargingTime(dischargingTime)
+        , m_level(ensureTwoSignificantDigits(level)) { }
+    BatteryStatus(const BatteryStatus&) = default;
+    BatteryStatus& operator=(const BatteryStatus&) = default;
+
+    bool charging() const { return m_charging; }
+    double chargingTime() const  { return m_chargingTime; }
+    double dischargingTime() const  { return m_dischargingTime; }
+    double level() const  { return m_level; }
+
+private:
+    double ensureTwoSignificantDigits(double level)
+    {
+        // Convert battery level value which should be in [0, 1] to a value in [0, 1]
+        // with 2 digits of precision. This is to provide a consistent experience
+        // across platforms (e.g. on Mac and Android the battery changes are generally
+        // reported with 1% granularity). It also serves the purpose of reducing the
+        // possibility of fingerprinting and triggers less level change events on
+        // platforms where the granularity is high.
+        ASSERT(level >= 0 && level <= 1);
+        return std::round(level * 100) / 100.f;
+    }
+
+    bool m_charging;
+    double m_chargingTime;
+    double m_dischargingTime;
+    double m_level;
+};
+
+} // namespace blink
+
+#endif // BatteryStatus_h