Remove DeviceMonitorLinux::WillDestroyCurrentMessageLoop().

device/usb/usb_service.cc

Index: device/usb/usb_service.cc
diff --git a/device/usb/usb_service.cc b/device/usb/usb_service.cc
index 1a2cf98c303515444602a615cffe05c55839ce07..223a5239ecaa57ac5a017043376699312370a622 100644
--- a/device/usb/usb_service.cc
+++ b/device/usb/usb_service.cc
@@ -51,6 +51,9 @@ std::unique_ptr<UsbService> UsbService::Create(
 }
 
 UsbService::~UsbService() {
+#if DCHECK_IS_ON()
+  DCHECK(did_shutdown_);
+#endif
   for (const auto& map_entry : devices_)
     map_entry.second->OnDisconnect();
   for (auto& observer : observer_list_)
@@ -70,6 +73,13 @@ scoped_refptr<UsbDevice> UsbService::GetDevice(const std::string& guid) {
   return it->second;
 }
 
+void UsbService::Shutdown() {
+#if DCHECK_IS_ON()
+  DCHECK(!did_shutdown_);
+  did_shutdown_ = true;
+#endif
+}
+
 void UsbService::GetDevices(const GetDevicesCallback& callback) {
   std::vector<scoped_refptr<UsbDevice>> devices;
   devices.reserve(devices_.size());