Disallow redundant Bind calls.

device/serial/data_sender.cc

 // Copyright 2014 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 "device/serial/data_sender.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 105 matching lines @@
 void DataSender::OnConnectionError() {
   ShutDown();
 }
 
 void DataSender::RunCancelCallback() {
   DCHECK(sends_awaiting_ack_.empty());
   if (pending_cancel_.is_null())
     return;
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
-                                                base::Bind(pending_cancel_));
-  pending_cancel_.Reset();

[danakj, 2016/09/24 01:20:01]

can you still reset after in case code checks if its null, or is move from
well-defined to leave it null for this?

[dcheng, 2016/09/24 01:29:56]

I'm going to add a unit test for this... but this reminds me...

This doesn't actually work for whatever reason. I'm going to revert this to the
naive version (just without the base::Bind) and debug / land some unit tests in
a followup.

+                                                std::move(pending_cancel_));
 }
 
 void DataSender::ShutDown() {
   shut_down_ = true;
   while (!sends_awaiting_ack_.empty()) {
     sends_awaiting_ack_.front()->DispatchFatalError();
     sends_awaiting_ack_.pop();
   }
   RunCancelCallback();
 }
@@ skipping 29 matching lines @@
 void DataSender::PendingSend::SendData() {
   uint32_t num_bytes_to_send = static_cast<uint32_t>(data_.size());
   mojo::Array<uint8_t> bytes(num_bytes_to_send);
   memcpy(&bytes[0], data_.data(), num_bytes_to_send);
   sender_->sink_->OnData(
       std::move(bytes),
       base::Bind(&DataSender::PendingSend::OnDataSent, base::Unretained(this)));
 }
 
 }  // namespace device