Fix a crash in SerialIoHandler.

device/serial/serial_io_handler.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/serial_io_handler.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_util.h"
@@ skipping 96 matching lines @@
   pending_write_buffer_ = buffer.Pass();
   write_canceled_ = false;
   AddRef();
   WriteImpl();
 }
 
 void SerialIoHandler::ReadCompleted(int bytes_read,
                                     serial::ReceiveError error) {
   DCHECK(CalledOnValidThread());
   DCHECK(IsReadPending());
+  scoped_ptr<WritableBuffer> pending_read_buffer = pending_read_buffer_.Pass();
   if (error == serial::RECEIVE_ERROR_NONE) {
-    pending_read_buffer_->Done(bytes_read);
+    pending_read_buffer->Done(bytes_read);
   } else {
-    pending_read_buffer_->DoneWithError(bytes_read, error);
+    pending_read_buffer->DoneWithError(bytes_read, error);
   }
-  pending_read_buffer_.reset();
   Release();
 }
 
 void SerialIoHandler::WriteCompleted(int bytes_written,
                                      serial::SendError error) {
   DCHECK(CalledOnValidThread());
   DCHECK(IsWritePending());
+  scoped_ptr<ReadOnlyBuffer> pending_write_buffer =
+      pending_write_buffer_.Pass();
   if (error == serial::SEND_ERROR_NONE) {
-    pending_write_buffer_->Done(bytes_written);
+    pending_write_buffer->Done(bytes_written);
   } else {
-    pending_write_buffer_->DoneWithError(bytes_written, error);
+    pending_write_buffer->DoneWithError(bytes_written, error);
   }
-  pending_write_buffer_.reset();
   Release();
 }
 
 bool SerialIoHandler::IsReadPending() const {
   DCHECK(CalledOnValidThread());
   return pending_read_buffer_ != NULL;
 }
 
 bool SerialIoHandler::IsWritePending() const {
   DCHECK(CalledOnValidThread());
@@ skipping 26 matching lines @@
 }
 
 void SerialIoHandler::QueueWriteCompleted(int bytes_written,
                                           serial::SendError error) {
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(&SerialIoHandler::WriteCompleted, this, bytes_written, error));
 }
 
 }  // namespace device