Disallow redundant Bind calls.

device/serial/data_sender.cc

Index: device/serial/data_sender.cc
diff --git a/device/serial/data_sender.cc b/device/serial/data_sender.cc
index 6f12750cbc9d79fbd36b0f59a46bdfdc0b4a0671..b83ddb647c90d690cd96c31998b478686bc52cb3 100644
--- a/device/serial/data_sender.cc
+++ b/device/serial/data_sender.cc
@@ -123,8 +123,7 @@ void DataSender::RunCancelCallback() {
     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() {