Make DeviceSensorService implement MainLoop::DestructionObserver

services/device/device_service.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 "services/device/device_service.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "services/device/fingerprint/fingerprint.h"
 #include "services/device/power_monitor/power_monitor_message_broadcaster.h"
 #include "services/device/time_zone_monitor/time_zone_monitor.h"
 #include "services/service_manager/public/cpp/connection.h"
 #include "services/service_manager/public/cpp/interface_registry.h"
 
 #if defined(OS_ANDROID)
+#include "base/trace_event/trace_event.h"
+#include "device/sensors/device_sensor_service.h"
 #include "services/device/android/register_jni.h"
 #endif
 
 namespace device {
 
 std::unique_ptr<service_manager::Service> CreateDeviceService(
     scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) {
 #if defined(OS_ANDROID)
   if (!EnsureJniRegistered()) {
     DLOG(ERROR) << "Failed to register JNI for Device Service";
     return nullptr;
   }
 #endif
 
   return base::MakeUnique<DeviceService>(std::move(file_task_runner));
 }
 
 DeviceService::DeviceService(
     scoped_refptr<base::SingleThreadTaskRunner> file_task_runner)
     : file_task_runner_(std::move(file_task_runner)) {}
 
-DeviceService::~DeviceService() {}
+DeviceService::~DeviceService() {
+#if defined(OS_ANDROID)
+  TRACE_EVENT0("shutdown", "DeviceService::Subsystem:SensorService");

[ke.he, 2017/03/08 09:19:55]

For Android platform, it is safe to shutdown in UI thread, no need to care about
whether IO thread is live or not.

[blundell, 2017/03/08 17:38:17]

Do you think that we could just use the same mechanism on Android as on other
platforms, i.e., have it observe the destruction of the message loop that it's
running on?

[ke.he, 2017/03/09 02:37:33]

For Android platform, DeviceSensorService runs in UI thread, it needs to get an
"io_task_runner" to add itself into IO MessageLoop's observer list.
DeviceSensorService is process singleton, it is created in
"DeviceSensorService::GetInstance()" when "DeviceSensorHost::StartPolling()" is
first called. so we need to pass the "io_task_runner" to DeviceSensorHost in
"RenderProcessHostImpl::AddUIThreadInterface(...)".

I'm not sure whether above make the code too complex, that's why I shutdown
DeviceSensorService-android here.

Please help to decide that should I add the "io_task_runner" in DeviceSensorHost
and DeviceSensorService? Thanks!

+  device::DeviceSensorService::GetInstance()->Shutdown();
+#endif
+}
 
 void DeviceService::OnStart() {}
 
 bool DeviceService::OnConnect(const service_manager::ServiceInfo& remote_info,
                               service_manager::InterfaceRegistry* registry) {
   registry->AddInterface<mojom::Fingerprint>(this);
   registry->AddInterface<mojom::PowerMonitor>(this);
   registry->AddInterface<mojom::TimeZoneMonitor>(this);
   return true;
 }
@@ skipping 13 matching lines @@
 }
 
 void DeviceService::Create(const service_manager::Identity& remote_identity,
                            mojom::TimeZoneMonitorRequest request) {
   if (!time_zone_monitor_)
     time_zone_monitor_ = device::TimeZoneMonitor::Create(file_task_runner_);
   time_zone_monitor_->Bind(std::move(request));
 }
 
 }  // namespace device