Avoid shutdown leak.

mojo/edk/system/message_pipe_dispatcher.cc

 // Copyright 2015 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/message_pipe_dispatcher.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 452 matching lines @@
   // posted task.
   if (!transferable_ && non_transferable_state_ == CLOSED)
     return;
 
   // We take a manual refcount because at shutdown, the task below might not get
   // a chance to execute. If that happens, the RawChannel will still call our
   // OnError method because it always runs (since it watches thread
   // destruction). So to avoid UAF, manually add a reference and only release it
   // if the task runs.
   AddRef();
-  internal::g_io_thread_task_runner->PostTask(
-      FROM_HERE, base::Bind(&MessagePipeDispatcher::CloseOnIOAndRelease, this));
+  if (!internal::g_io_thread_task_runner->PostTask(
+          FROM_HERE,
+          base::Bind(&MessagePipeDispatcher::CloseOnIOAndRelease, this))) {
+    // Avoid a shutdown leak in unittests. If the thread is shutting down,
+    // we can't connect to the other end to let it know that we're closed either
+    // way.
+    if (!transferable_ && non_transferable_state_ == WAITING_FOR_READ_OR_WRITE)
+      Release();
+  }
 }
 
 void MessagePipeDispatcher::SerializeInternal() {
   serialized_ = true;
   if (!transferable_) {
     CHECK(non_transferable_state_ == WAITING_FOR_READ_OR_WRITE)
         << "Non transferable message pipe being sent after read/write/waited. "
         << "MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_TRANSFERABLE must be used if "
         << "the pipe can be sent after it's read or written. This message pipe "
         << "was previously bound at:\n"
@@ skipping 597 matching lines @@
   // PostTask since the broker can call us back synchronously.
   internal::g_io_thread_task_runner->PostTask(
       FROM_HERE,
       base::Bind(&Broker::ConnectMessagePipe,
                  base::Unretained(internal::g_broker), pipe_id_,
                  base::Unretained(this)));
 }
 
 }  // namespace edk
 }  // namespace mojo