Use thread-safe send when using Mojo.

ipc/mojo/ipc_channel_mojo.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 "ipc/mojo/ipc_channel_mojo.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/lazy_instance.h"
 #include "base/thread_task_runner_handle.h"
@@ skipping 429 matching lines @@
     pending_messages_.push_back(message);
     // Counts as OK before the connection is established, but it's an
     // error otherwise.
     return waiting_connect_;
   }
 
   return message_reader_->Send(make_scoped_ptr(message));
 }
 
 bool ChannelMojo::IsSendThreadSafe() const {
-  return false;
+  return true;
 }
 
 base::ProcessId ChannelMojo::GetPeerPID() const {
   return peer_pid_;
 }
 
 base::ProcessId ChannelMojo::GetSelfPID() const {
   return bootstrap_->GetSelfPID();
 }
 
@@ skipping 90 matching lines @@
     if (!ok) {
       LOG(ERROR) << "Failed to add new Mojo handle.";
       return MOJO_RESULT_UNKNOWN;
     }
   }
 
   return MOJO_RESULT_OK;
 }
 
 }  // namespace IPC