Adds some code to help isolate where crash is happening

mojo/environment/default_async_waiter_impl.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 "mojo/environment/default_async_waiter_impl.h"
 
 #include "base/bind.h"
 #include "mojo/message_pump/handle_watcher.h"
 
 namespace mojo {
 namespace internal {
 namespace {
 
 void OnHandleReady(common::HandleWatcher* watcher,
                    MojoAsyncWaitCallback callback,
                    void* closure,
                    MojoResult result) {
   delete watcher;
   callback(closure, result);
 }
 
-MojoAsyncWaitID AsyncWait(MojoHandle handle,
+MojoAsyncWaitID AsyncWait(int id,
+                          MojoHandle handle,
                           MojoHandleSignals signals,
                           MojoDeadline deadline,
                           MojoAsyncWaitCallback callback,
                           void* closure) {
   // This instance will be deleted when done or cancelled.
-  common::HandleWatcher* watcher = new common::HandleWatcher();
+  common::HandleWatcher* watcher = new common::HandleWatcher(id);
   watcher->Start(Handle(handle), signals, deadline,
                  base::Bind(&OnHandleReady, watcher, callback, closure));
   return reinterpret_cast<MojoAsyncWaitID>(watcher);
 }
 
 void CancelWait(MojoAsyncWaitID wait_id) {
   delete reinterpret_cast<common::HandleWatcher*>(wait_id);
 }
 
 const MojoAsyncWaiter kDefaultAsyncWaiter = {
   AsyncWait,
   CancelWait
 };
 
 }  // namespace
 
 const MojoAsyncWaiter* GetDefaultAsyncWaiterImpl() {
   return &kDefaultAsyncWaiter;
 }
 
 }  // namespace internal
 }  // namespace mojo