[device] Replace MessageLoopProxy usage with ThreadTaskRunnerHandle

device/serial/serial_io_handler.cc

Index: device/serial/serial_io_handler.cc
diff --git a/device/serial/serial_io_handler.cc b/device/serial/serial_io_handler.cc
index 288e7618c42d6c729f889eb0f8da53e0c6a01c76..ddae198441fae111bf80e0a8462b9af07ac01047 100644
--- a/device/serial/serial_io_handler.cc
+++ b/device/serial/serial_io_handler.cc
@@ -12,8 +12,8 @@
 namespace device {
 
 SerialIoHandler::SerialIoHandler(
-    scoped_refptr<base::MessageLoopProxy> file_thread_message_loop,
-    scoped_refptr<base::MessageLoopProxy> ui_thread_message_loop)
+    scoped_refptr<base::SingleThreadTaskRunner> file_thread_message_loop,
+    scoped_refptr<base::SingleThreadTaskRunner> ui_thread_message_loop)
     : file_thread_message_loop_(file_thread_message_loop),
       ui_thread_message_loop_(ui_thread_message_loop) {
   options_.bitrate = 9600;
@@ -43,8 +43,8 @@ void SerialIoHandler::Open(const std::string& port,
 
 void SerialIoHandler::RequestAccess(
     const std::string& port,
-    scoped_refptr<base::MessageLoopProxy> file_message_loop,
-    scoped_refptr<base::MessageLoopProxy> ui_message_loop) {
+    scoped_refptr<base::SingleThreadTaskRunner> file_message_loop,
+    scoped_refptr<base::SingleThreadTaskRunner> ui_message_loop) {
   OnRequestAccessComplete(port, true /* success */);
 }
 
@@ -54,11 +54,8 @@ void SerialIoHandler::OnRequestAccessComplete(const std::string& port,
   if (success) {
     DCHECK(file_thread_message_loop_.get());
     file_thread_message_loop_->PostTask(
-        FROM_HERE,
-        base::Bind(&SerialIoHandler::StartOpen,
-                   this,
-                   port,
-                   base::MessageLoopProxy::current()));
+        FROM_HERE, base::Bind(&SerialIoHandler::StartOpen, this, port,
+                              base::ThreadTaskRunnerHandle::Get()));
     return;
   } else {
     DCHECK(!open_complete_.is_null());
@@ -91,7 +88,7 @@ void SerialIoHandler::MergeConnectionOptions(
 
 void SerialIoHandler::StartOpen(
     const std::string& port,
-    scoped_refptr<base::MessageLoopProxy> io_message_loop) {
+    scoped_refptr<base::SingleThreadTaskRunner> io_message_loop) {
   DCHECK(!open_complete_.is_null());
   DCHECK(file_thread_message_loop_->RunsTasksOnCurrentThread());
   DCHECK(!file_.IsValid());