base: Support setting thread priorities generically.

base/threading/platform_thread_mac.mm

 // 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"
 
 #import <Foundation/Foundation.h>
 #include <dlfcn.h>
 #include <mach/mach.h>
 #include <mach/mach_time.h>
@@ skipping 143 matching lines @@
   if (result != KERN_SUCCESS)
     DVLOG(1) << "thread_policy_set() failure: " << result;
 
   return;
 }
 
 }  // anonymous namespace
 
 // static
 void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
+                                       PlatformThreadId,
                                        ThreadPriority priority) {
   // Convert from pthread_t to mach thread identifier.
   mach_port_t mach_thread_id = pthread_mach_thread_np(handle);
 
   switch (priority) {
     case kThreadPriority_Normal:
       SetPriorityNormal(mach_thread_id);
       break;
     case kThreadPriority_RealtimeAudio:
       SetPriorityRealtimeAudio(mach_thread_id);
       break;
+    default:
+      NOTREACHED() << "Unknown priority.";
+      break;
   }
 }
 
 }  // namespace base