Mojo: More plumbing to support sending handles over MessagePipes.

mojo/system/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/system/dispatcher.h"
 
 #include "base/logging.h"
 #include "mojo/system/limits.h"
 
 namespace mojo {
@@ skipping 20 matching lines @@
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return WriteMessageImplNoLock(bytes, num_bytes, dispatchers, flags);
 }
 
 MojoResult Dispatcher::ReadMessage(
     void* bytes, uint32_t* num_bytes,
     uint32_t max_num_dispatchers,
     std::vector<scoped_refptr<Dispatcher> >* dispatchers,
     MojoReadMessageFlags flags) {
-  DCHECK(max_num_dispatchers == 0 || !!dispatchers);
+  DCHECK(max_num_dispatchers == 0 || (dispatchers && dispatchers->empty()));
 
   base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return ReadMessageImplNoLock(bytes, num_bytes,
                                max_num_dispatchers, dispatchers,
                                flags);
 }
 
@@ skipping 75 matching lines @@
 
 void Dispatcher::RemoveWaiterImplNoLock(Waiter* waiter) {
   lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, waiting isn't supported. Only dispatchers that can be waited on
   // will do something nontrivial.
 }
 
 }  // namespace system
 }  // namespace mojo