Reland: Lazily initialize MessageLoop for faster thread startup

net/test/embedded_test_server/embedded_test_server.cc

 // Copyright (c) 2012 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 "net/test/embedded_test_server/embedded_test_server.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 172 matching lines @@
   return PostTaskToIOThreadAndWait(base::Bind(
       &EmbeddedTestServer::ShutdownOnIOThread, base::Unretained(this)));
 }
 
 void EmbeddedTestServer::StartThread() {
   DCHECK(!io_thread_.get());
   base::Thread::Options thread_options;
   thread_options.message_loop_type = base::MessageLoop::TYPE_IO;
   io_thread_.reset(new base::Thread("EmbeddedTestServer io thread"));
   CHECK(io_thread_->StartWithOptions(thread_options));
+  CHECK(io_thread_->WaitUntilThreadStarted());
 }
 
 void EmbeddedTestServer::InitializeOnIOThread() {
   DCHECK(io_thread_->message_loop_proxy()->BelongsToCurrentThread());
   DCHECK(!Started());
 
   SocketDescriptor socket_descriptor =
       TCPListenSocket::CreateAndBindAnyPort("127.0.0.1", &port_);
   if (socket_descriptor == kInvalidSocket)
     return;
@@ skipping 150 matching lines @@
           FROM_HERE, closure, run_loop.QuitClosure())) {
     return false;
   }
   run_loop.Run();
 
   return true;
 }
 
 }  // namespace test_server
 }  // namespace net