[sensors](Linux) Fix tsan data race in sensor reader

device/generic_sensor/platform_sensor_linux.cc

Index: device/generic_sensor/platform_sensor_linux.cc
diff --git a/device/generic_sensor/platform_sensor_linux.cc b/device/generic_sensor/platform_sensor_linux.cc
index 55aa1398d1499c7bd61bfc4ec10b1199b5087c85..0252f2e30dc822f10745736e7aa09cb84af23ef5 100644
--- a/device/generic_sensor/platform_sensor_linux.cc
+++ b/device/generic_sensor/platform_sensor_linux.cc
@@ -24,17 +24,23 @@ PlatformSensorLinux::PlatformSensorLinux(
     mojo::ScopedSharedBufferMapping mapping,
     PlatformSensorProvider* provider,
     const SensorInfoLinux* sensor_device,
+    std::unique_ptr<SensorReader> sensor_reader,
     scoped_refptr<base::SingleThreadTaskRunner> polling_thread_task_runner)
     : PlatformSensor(type, std::move(mapping), provider),
       default_configuration_(
           PlatformSensorConfiguration(sensor_device->device_frequency)),
       reporting_mode_(sensor_device->reporting_mode),
+      polling_thread_task_runner_(std::move(polling_thread_task_runner)),
+      sensor_reader_(std::move(sensor_reader)),
       weak_factory_(this) {
-  sensor_reader_ =
-      SensorReader::Create(sensor_device, this, polling_thread_task_runner);
+  DCHECK(sensor_reader_);
+  sensor_reader_->SetPlatformSensorLinux(this);
 }
 
-PlatformSensorLinux::~PlatformSensorLinux() = default;
+PlatformSensorLinux::~PlatformSensorLinux() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  polling_thread_task_runner_->DeleteSoon(FROM_HERE, sensor_reader_.release());
+}
 
 mojom::ReportingMode PlatformSensorLinux::GetReportingMode() {
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ -62,15 +68,18 @@ void PlatformSensorLinux::NotifyPlatformSensorError() {
 bool PlatformSensorLinux::StartSensor(
     const PlatformSensorConfiguration& configuration) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  if (!sensor_reader_)
-    return false;
-  return sensor_reader_->StartFetchingData(configuration);
+  polling_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&SensorReader::StartFetchingData,
+                 base::Unretained(sensor_reader_.get()), configuration));
+  return true;
 }
 
 void PlatformSensorLinux::StopSensor() {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK(sensor_reader_);
-  sensor_reader_->StopFetchingData();
+  polling_thread_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&SensorReader::StopFetchingData,
+                            base::Unretained(sensor_reader_.get())));
 }
 
 bool PlatformSensorLinux::CheckSensorConfiguration(