[sensors] Introduce Generic Sensor API interfaces

device/generic_sensor/sensor_provider_impl.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/sensor_provider_impl.h"
+
+#include <utility>
+
+#include "device/generic_sensor/platform_sensor_provider.h"
+#include "device/generic_sensor/sensor_impl.h"
+
+namespace device {
+
+namespace {
+
+uint64_t GetBufferOffset(mojom::SensorType type) {
+  return (static_cast<uint64_t>(mojom::SensorType::LAST) -
+          static_cast<uint64_t>(type)) *
+         mojom::SensorReadBuffer::kReadBufferSize;
+}
+
+}  // namespace
+
+// static
+void SensorProviderImpl::Create(
+    mojo::InterfaceRequest<mojom::SensorProvider> request) {
+  PlatformSensorProvider* provider = PlatformSensorProvider::GetInstance();
+  if (provider)
+    new SensorProviderImpl(std::move(request), provider);
+}
+
+SensorProviderImpl::SensorProviderImpl(
+    mojo::InterfaceRequest<mojom::SensorProvider> request,
+    PlatformSensorProvider* provider)
+    : binding_(this, std::move(request)), provider_(provider) {
+  DCHECK(provider_);
+}
+
+SensorProviderImpl::~SensorProviderImpl() {}
+
+void SensorProviderImpl::GetSensor(mojom::SensorType type,
+                                   mojom::SensorRequest sensor_request,
+                                   const GetSensorCallback& callback) {
+  auto cloned_handle = provider_->CloneSharedBufferHandle();
+  if (!cloned_handle.is_valid()) {
+    callback.Run(nullptr, nullptr);
+    return;
+  }
+
+  scoped_refptr<PlatformSensor> sensor = provider_->GetSensor(type);
+  if (!sensor) {
+    sensor = provider_->CreateSensor(
+        type, mojom::SensorReadBuffer::kReadBufferSize, GetBufferOffset(type));
+  }
+
+  if (!sensor) {
+    callback.Run(nullptr, nullptr);
+    return;
+  }
+
+  auto sensor_impl = new SensorImpl(std::move(sensor_request), sensor);
+
+  auto sensor_read_buffer = mojom::SensorReadBuffer::New();
+  sensor_read_buffer->memory = std::move(cloned_handle);
+  sensor_read_buffer->offset = GetBufferOffset(type);
+  sensor_read_buffer->mode = sensor->GetReportingMode();
+
+  callback.Run(std::move(sensor_read_buffer), sensor_impl->GetClient());
+}
+
+}  // namespace device