Mojo EDK: Add tests to exercise races in handle transit

mojo/edk/system/data_pipe_producer_dispatcher.cc

 // Copyright 2013 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 "mojo/edk/system/data_pipe_producer_dispatcher.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 385 matching lines @@
       new DataPipeProducerDispatcher(node_controller, port, ring_buffer,
                                      state->options, false /* initialized */,
                                      state->pipe_id);
 
   {
     base::AutoLock lock(dispatcher->lock_);
     dispatcher->write_offset_ = state->write_offset;
     dispatcher->available_capacity_ = state->available_capacity;
     dispatcher->peer_closed_ = state->flags & kFlagPeerClosed;
     dispatcher->InitializeNoLock();
+    dispatcher->UpdateSignalsStateNoLock();
   }
 
   return dispatcher;
 }
 
 DataPipeProducerDispatcher::~DataPipeProducerDispatcher() {
   DCHECK(is_closed_ && !in_transit_ && !shared_ring_buffer_ &&
          !ring_buffer_mapping_);
 }
 
@@ skipping 124 matching lines @@
   }
 
   if (peer_closed_ != was_peer_closed ||
       available_capacity_ != previous_capacity) {
     awakable_list_.AwakeForStateChange(GetHandleSignalsStateNoLock());
   }
 }
 
 }  // namespace edk
 }  // namespace mojo