Add data pipe wrappers to be used to implement serial receive.

device/serial/async_waiter.h

+// 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.
+
+#ifndef DEVICE_SERIAL_ASYNC_WAITER_H_
+#define DEVICE_SERIAL_ASYNC_WAITER_H_
+
+#include "base/callback.h"
+#include "mojo/public/c/environment/async_waiter.h"
+#include "mojo/public/cpp/environment/environment.h"
+#include "mojo/public/cpp/system/handle.h"
+
+namespace device {
+
+// A class that waits until a handle is ready and calls |callback| with the
+// result. If the AsyncWaiter is deleted before the handle is ready, the wait is
+// cancelled and the callback will not be called.
+class AsyncWaiter {
+ public:
+  typedef base::Callback<void(MojoResult)> Callback;
+
+  AsyncWaiter(mojo::Handle handle,
+              MojoHandleSignals signals,
+              const Callback& callback);
+  ~AsyncWaiter();
+
+ private:
+  static void WaitComplete(void* waiter, MojoResult result);
+  void WaitCompleteInternal(MojoResult result);
+
+  const MojoAsyncWaiter* waiter_;
+  MojoAsyncWaitID id_;
+  const Callback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(AsyncWaiter);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_SERIAL_ASYNC_WAITER_H_