Removing file_thread_task_runner parameter from SerialIoHandler

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 b73d532d09ebb797263095e4f264799ceb74cb99..1c614364d6794c7791bfef646c6c9b6f29c4aacf 100644
--- a/device/serial/serial_io_handler.cc
+++ b/device/serial/serial_io_handler.cc
@@ -21,10 +21,8 @@
 namespace device {
 
 SerialIoHandler::SerialIoHandler(
-    scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> ui_thread_task_runner)
-    : file_thread_task_runner_(file_thread_task_runner),
-      ui_thread_task_runner_(ui_thread_task_runner) {
+    : ui_thread_task_runner_(ui_thread_task_runner) {
   options_.bitrate = 9600;
   options_.data_bits = serial::DataBits::EIGHT;
   options_.parity_bit = serial::ParityBit::NO_PARITY;
@@ -35,7 +33,6 @@ SerialIoHandler::SerialIoHandler(
 
 SerialIoHandler::~SerialIoHandler() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  Close();
 }
 
 void SerialIoHandler::Open(const std::string& port,
@@ -44,7 +41,6 @@ void SerialIoHandler::Open(const std::string& port,
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK(open_complete_.is_null());
   open_complete_ = callback;
-  DCHECK(file_thread_task_runner_.get());
   DCHECK(ui_thread_task_runner_.get());
   MergeConnectionOptions(options);
   port_ = port;
@@ -62,10 +58,6 @@ void SerialIoHandler::Open(const std::string& port,
           &chromeos::PermissionBrokerClient::OpenPath, base::Unretained(client),
           port, base::Bind(&SerialIoHandler::OnPathOpened, this, task_runner),
           base::Bind(&SerialIoHandler::OnPathOpenError, this, task_runner)));
-#else
-  file_thread_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&SerialIoHandler::StartOpen, this, port,
-                            base::ThreadTaskRunnerHandle::Get()));

[Reilly Grant (use Gerrit), 2017/06/01 13:48:21]

file_thread_task_runner_ is clearly used here so the original issue was wrong to
say it was completely unused. However we can replace this statement with,

base::PostTaskWithTraits(
    FROM_HERE,
    {base::MayBlock(), base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
    base::Bind(&SerialIoHandler::StartOpen, this, port,	
               base::ThreadTaskRunnerHandle::Get()));

[sujith, 2017/06/01 14:57:31]

Done.

 #endif  // defined(OS_CHROMEOS)
 }
 
@@ -126,7 +118,6 @@ void SerialIoHandler::StartOpen(
     const std::string& port,
     scoped_refptr<base::SingleThreadTaskRunner> io_task_runner) {
   DCHECK(!open_complete_.is_null());
-  DCHECK(file_thread_task_runner_->RunsTasksInCurrentSequence());
   DCHECK(!file_.IsValid());
   // It's the responsibility of the API wrapper around SerialIoHandler to
   // validate the supplied path against the set of valid port names, and
@@ -158,8 +149,6 @@ void SerialIoHandler::FinishOpen(base::File file) {
   file_ = std::move(file);
 
   bool success = PostOpen() && ConfigurePortImpl();
-  if (!success)
-    Close();
 
   callback.Run(success);
 }
@@ -168,15 +157,6 @@ bool SerialIoHandler::PostOpen() {
   return true;
 }
 
-void SerialIoHandler::Close() {
-  if (file_.IsValid()) {
-    DCHECK(file_thread_task_runner_.get());
-    file_thread_task_runner_->PostTask(

[Reilly Grant (use Gerrit), 2017/06/01 13:48:21]

Same here. We can't just remove the Close method. Please keep this method and
use base::PostTaskWithTraits instead.

[sujith, 2017/06/01 14:57:31]

Done.

-        FROM_HERE,
-        base::Bind(&SerialIoHandler::DoClose, Passed(std::move(file_))));
-  }
-}
-
 // static
 void SerialIoHandler::DoClose(base::File port) {
   // port closed by destructor.