Remove DeviceLightEvent implementation

device/generic_sensor/platform_sensor_ambient_light_mac.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 "device/generic_sensor/platform_sensor_ambient_light_mac.h"
 
+#include <stdint.h>
+
 #include <IOKit/IOMessage.h>
 
 #include "base/bind.h"
 #include "device/base/synchronization/shared_memory_seqlock_buffer.h"
+#include "device/generic_sensor/generic_sensor_consts.h"
 #include "device/generic_sensor/platform_sensor_provider_mac.h"
-#include "device/sensors/public/cpp/device_sensors_consts.h"
-#include "device/sensors/public/cpp/device_util_mac.h"
+
+namespace {
+
+// Convert the value returned by the ambient light LMU sensor on Mac
+// hardware to a lux value.
+double LMUvalueToLux(uint64_t raw_value) {
+  // Conversion formula from regression.
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=793728
+  // Let x = raw_value, then
+  // lux = -2.978303814*(10^-27)*x^4 + 2.635687683*(10^-19)*x^3 -
+  //       3.459747434*(10^-12)*x^2 + 3.905829689*(10^-5)*x - 0.1932594532
+
+  static const long double k4 = pow(10.L, -7);
+  static const long double k3 = pow(10.L, -4);
+  static const long double k2 = pow(10.L, -2);
+  static const long double k1 = pow(10.L, 5);
+  long double scaled_value = raw_value / k1;
+
+  long double lux_value =
+      (-3 * k4 * pow(scaled_value, 4)) + (2.6 * k3 * pow(scaled_value, 3)) +
+      (-3.4 * k2 * pow(scaled_value, 2)) + (3.9 * scaled_value) - 0.19;
+
+  double lux = ceil(static_cast<double>(lux_value));
+  return lux > 0 ? lux : 0;
+}
+
+}  // namespace
 
 namespace device {
 
 enum LmuFunctionIndex {
   kGetSensorReadingID = 0,  // getSensorReading(int *, int *)
 };
 
 PlatformSensorAmbientLightMac::PlatformSensorAmbientLightMac(
     mojom::SensorType type,
     mojo::ScopedSharedBufferMapping mapping,
@@ skipping 115 matching lines @@
   current_lux_ = lux;
 
   SensorReading reading;
   reading.timestamp = (base::TimeTicks::Now() - base::TimeTicks()).InSecondsF();
   reading.values[0] = current_lux_;
   UpdateSensorReading(reading, true);
   return true;
 }
 
 }  // namespace device