Move mojo::{Wait,WaitMany}() to (the newly-added) mojo/public/cpp/system/wait.h.

mojo/public/cpp/test_support/lib/test_utils.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/public/cpp/test_support/test_utils.h"
 
 #include "mojo/public/cpp/system/handle.h"
 #include "mojo/public/cpp/system/message_pipe.h"
+#include "mojo/public/cpp/system/wait.h"
 
 namespace mojo {
 namespace test {
 
 bool WriteTextMessage(const MessagePipeHandle& handle,
                       const std::string& text) {
   MojoResult rv =
       WriteMessageRaw(handle, text.data(), static_cast<uint32_t>(text.size()),
                       nullptr, 0u, MOJO_WRITE_MESSAGE_FLAG_NONE);
   return rv == MOJO_RESULT_OK;
@@ skipping 31 matching lines @@
 }
 
 bool DiscardMessage(const MessagePipeHandle& handle) {
   MojoResult rv = ReadMessageRaw(handle, nullptr, nullptr, nullptr, nullptr,
                                  MOJO_READ_MESSAGE_FLAG_MAY_DISCARD);
   return rv == MOJO_RESULT_OK;
 }
 
 }  // namespace test
 }  // namespace mojo