Remove NOTIMPLEMENTED() from PlatformThread::SetThreadPriority() for posix.

base/threading/platform_thread_win.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 "base/threading/platform_thread.h"
 
 #include "base/debug/alias.h"
 #include "base/logging.h"
 #include "base/threading/thread_local.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 168 matching lines @@
 // static
 void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
                                        ThreadPriority priority) {
   switch (priority) {
     case kThreadPriority_Normal:
       ::SetThreadPriority(handle, THREAD_PRIORITY_NORMAL);
       break;
     case kThreadPriority_RealtimeAudio:
       ::SetThreadPriority(handle, THREAD_PRIORITY_TIME_CRITICAL);
       break;
-    default:
-      NOTIMPLEMENTED();
-      break;
   }
 }
 
 }  // namespace base