Revert of Move //device/generic_sensor to be part of the internal implementation of the Device Service.

device/generic_sensor/platform_sensor_provider_base.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_provider_base.h"
+
+#include <utility>
+
+#include "base/stl_util.h"
+#include "device/generic_sensor/public/interfaces/sensor_provider.mojom.h"
+
+namespace device {
+
+namespace {
+
+const uint64_t kReadingBufferSize = sizeof(SensorReadingSharedBuffer);
+const uint64_t kSharedBufferSizeInBytes =
+    kReadingBufferSize * static_cast<uint64_t>(mojom::SensorType::LAST);
+
+}  // namespace
+
+PlatformSensorProviderBase::PlatformSensorProviderBase() = default;
+
+PlatformSensorProviderBase::~PlatformSensorProviderBase() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+}
+
+void PlatformSensorProviderBase::CreateSensor(
+    mojom::SensorType type,
+    const CreateSensorCallback& callback) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+
+  if (!CreateSharedBufferIfNeeded()) {
+    callback.Run(nullptr);
+    return;
+  }
+
+  mojo::ScopedSharedBufferMapping mapping = MapSharedBufferForType(type);
+  if (!mapping) {
+    callback.Run(nullptr);
+    return;
+  }
+
+  auto it = requests_map_.find(type);
+  if (it != requests_map_.end()) {
+    it->second.push_back(callback);
+  } else {  // This is the first CreateSensor call.
+    requests_map_[type] = CallbackQueue({callback});
+
+    CreateSensorInternal(
+        type, std::move(mapping),
+        base::Bind(&PlatformSensorProviderBase::NotifySensorCreated,
+                   base::Unretained(this), type));
+  }
+}
+
+scoped_refptr<PlatformSensor> PlatformSensorProviderBase::GetSensor(
+    mojom::SensorType type) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+
+  auto it = sensor_map_.find(type);
+  if (it != sensor_map_.end())
+    return it->second;
+  return nullptr;
+}
+
+bool PlatformSensorProviderBase::CreateSharedBufferIfNeeded() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  if (shared_buffer_handle_.is_valid())
+    return true;
+
+  shared_buffer_handle_ =
+      mojo::SharedBufferHandle::Create(kSharedBufferSizeInBytes);
+  return shared_buffer_handle_.is_valid();
+}
+
+void PlatformSensorProviderBase::RemoveSensor(mojom::SensorType type) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(ContainsKey(sensor_map_, type));
+  sensor_map_.erase(type);
+
+  if (sensor_map_.empty()) {
+    AllSensorsRemoved();
+    shared_buffer_handle_.reset();
+  }
+}
+
+mojo::ScopedSharedBufferHandle
+PlatformSensorProviderBase::CloneSharedBufferHandle() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  CreateSharedBufferIfNeeded();
+  return shared_buffer_handle_->Clone(
+      mojo::SharedBufferHandle::AccessMode::READ_ONLY);
+}
+
+bool PlatformSensorProviderBase::HasSensors() const {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  return !sensor_map_.empty();
+}
+
+void PlatformSensorProviderBase::NotifySensorCreated(
+    mojom::SensorType type,
+    scoped_refptr<PlatformSensor> sensor) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(!ContainsKey(sensor_map_, type));
+  DCHECK(ContainsKey(requests_map_, type));
+
+  if (sensor)
+    sensor_map_[type] = sensor.get();
+
+  // Inform subscribers about the sensor.
+  // |sensor| can be nullptr here.
+  auto it = requests_map_.find(type);
+  for (auto& callback : it->second)
+    callback.Run(sensor);
+
+  requests_map_.erase(type);
+}
+
+std::vector<mojom::SensorType>
+PlatformSensorProviderBase::GetPendingRequestTypes() {
+  std::vector<mojom::SensorType> request_types;
+  for (auto const& entry : requests_map_)
+    request_types.push_back(entry.first);
+  return request_types;
+}
+
+mojo::ScopedSharedBufferMapping
+PlatformSensorProviderBase::MapSharedBufferForType(mojom::SensorType type) {
+  mojo::ScopedSharedBufferMapping mapping = shared_buffer_handle_->MapAtOffset(
+      kReadingBufferSize, SensorReadingSharedBuffer::GetOffset(type));
+  memset(mapping.get(), 0, kReadingBufferSize);
+  return mapping;
+}
+
+}  // namespace device