[sensors] Introduce Generic Sensor API interfaces

device/generic_sensor/platform_sensor_provider.h

+// 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.
+
+#ifndef DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_PROVIDER_H_
+#define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_PROVIDER_H_
+
+#include "device/generic_sensor/platform_sensor_provider_base.h"
+
+namespace device {
+
+// This a singleton class returning the actual sensor provider
+// implementation for the current platform.
+class PlatformSensorProvider : public PlatformSensorProviderBase {
+ public:
+  // Returns the PlatformSensorProvider singleton.
+  // Note: returns 'nullptr' if there is no available implementation for
+  // the current platform.
+  static PlatformSensorProvider* GetInstance();
+
+ protected:
+  PlatformSensorProvider() = default;
+  ~PlatformSensorProvider() override = default;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorProvider);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_PROVIDER_H_