Make some fields non-nullable in serial.mojom and data_stream.mojom.

device/serial/data_source_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_source_sender.h"
 
 #include <limits>
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 72 matching lines @@
   ready_callback_.Reset();
   error_callback_.Reset();
 }
 
 DataSourceSender::~DataSourceSender() {
   DCHECK(shut_down_);
 }
 
 void DataSourceSender::Init(mojo::ScopedDataPipeProducerHandle handle) {
   // This should never occur. |handle_| is only valid and |pending_send_| is
-  // only set after Init is called. Receiving an invalid |handle| from the
-  // client is also unrecoverable.
-  if (pending_send_ || handle_.is_valid() || !handle.is_valid() || shut_down_) {
+  // only set after Init is called.
+  if (pending_send_ || handle_.is_valid() || shut_down_) {
     DispatchFatalError();
     return;
   }
   handle_ = handle.Pass();
   pending_send_.reset(new PendingSend(this, ready_callback_));
   StartWaiting();
 }
 
 void DataSourceSender::Resume() {
   if (pending_send_ || !handle_.is_valid()) {
@@ skipping 134 matching lines @@
     int32_t error) {
   DCHECK(sender_.get());
   pending_send_->DoneWithError(bytes_written, error);
   sender_ = NULL;
   pending_send_ = NULL;
   buffer_ = NULL;
   buffer_size_ = 0;
 }
 
 }  // namespace device