Add support for real-time audio threads.

base/threading/platform_thread_posix.cc

 // Copyright (c) 2011 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 "base/threading/platform_thread.h"
 
 #include <errno.h>
 #include <sched.h>
 
 #include "base/logging.h"
@@ skipping 204 matching lines @@
 
 // static
 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
   // Joining another thread may block the current thread for a long time, since
   // the thread referred to by |thread_handle| may still be running long-lived /
   // blocking tasks.
   base::ThreadRestrictions::AssertIOAllowed();
   pthread_join(thread_handle, NULL);
 }
 
+#if !defined(OS_MACOSX)
+// static
+void PlatformThread::EnableRealtimeAudioPerformance(PlatformThreadHandle) {
+  // TODO(crogers): implement
+}
+#endif
+
 }  // namespace base