[sensors] Introduce Generic Sensor API interfaces

device/sensors/platform_sensor_provider.h

Index: device/sensors/platform_sensor_provider.h
diff --git a/device/sensors/platform_sensor_provider.h b/device/sensors/platform_sensor_provider.h
new file mode 100644
index 0000000000000000000000000000000000000000..bc342cb6b71f8bbf23150bbff0b4fb997d1902f4
--- /dev/null
+++ b/device/sensors/platform_sensor_provider.h
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+// 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_SENSORS_PLATFORM_SENSOR_PROVIDER_H_
+#define DEVICE_SENSORS_PLATFORM_SENSOR_PROVIDER_H_
+
+#include "base/macros.h"
+
+#include "base/threading/non_thread_safe.h"
+#include "device/sensors/platform_sensor.h"
+
+namespace device {
+
+// Base class that defines factory methods for PlatformSensor creation.
+class PlatformSensorProvider : public base::NonThreadSafe {
+ public:
+  static PlatformSensorProvider* Create(uint64_t shared_buffer_size);
+
+  // Creates new instance of PlatformSensor.
+  scoped_refptr<PlatformSensor> CreateSensor(SensorType type,
+                                             uint64_t size,
+                                             uint64_t offset);
+
+  // Gets previously created instance of PlatformSensor by sensor type |type|.
+  scoped_refptr<PlatformSensor> GetSensor(SensorType type);
+
+  // Shared buffer getters.
+  mojo::ScopedSharedBufferHandle GetClonedSharedBufferHandle();
+
+ protected:
+  explicit PlatformSensorProvider(uint64_t shared_buffer_size);
+  virtual ~PlatformSensorProvider();
+
+  // Method that must be implemented by platform specific classes.
+  virtual scoped_refptr<PlatformSensor> CreateSensor(
+      SensorType type,
+      mojo::ScopedSharedBufferMapping mapping,
+      uint64_t buffer_size) = 0;
+
+ private:
+  bool CreateSharedBufferIfNeeded();
+
+  friend class PlatformSensor;  // To call RemoveSensor();
+  void RemoveSensor(SensorType type);
+
+ private:
+  using SensorMap = std::map<SensorType, PlatformSensor*>;
+  SensorMap sensor_map_;
+  mojo::ScopedSharedBufferHandle shared_buffer_handle_;
+  uint64_t shared_buffer_size_;
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorProvider);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_SENSORS_PLATFORM_SENSOR_PROVIDER_H_