Add support for real-time audio threads.

base/threading/platform_thread.h

 // 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.
 
 // WARNING: You should *NOT* be using this class directly.  PlatformThread is
 // the low-level platform-specific abstraction to the OS's threading interface.
 // You should instead be using a message-loop driven Thread, see thread.h.
 
 #ifndef BASE_THREADING_PLATFORM_THREAD_H_
 #define BASE_THREADING_PLATFORM_THREAD_H_
@@ skipping 73 matching lines @@
   // CreateNonJoinable() does the same thing as Create() except the thread
   // cannot be Join()'d.  Therefore, it also does not output a
   // PlatformThreadHandle.
   static bool CreateNonJoinable(size_t stack_size, Delegate* delegate);
 
   // Joins with a thread created via the Create function.  This function blocks
   // the caller until the designated thread exits.  This will invalidate
   // |thread_handle|.
   static void Join(PlatformThreadHandle thread_handle);
 
+  // Enables time-contraint policy and priority suitable for low-latency,
+  // glitch-resistant audio.
+  static void EnableRealtimeAudioPerformance(PlatformThreadHandle handle);

[Ken Russell (switch to Gerrit), 2011/05/09 22:28:14]

An audio-specific method seems out of place in this low-level class. Can you
think of a different way to name or specify this that would have the same
effect? For example, what about passing in the time constraint parameters in
some form, which might be ignored on other operating systems, and then name this
method generically? Or what about not making the Mac implementation not quite so
audio-specific, and call it something like "BoostThreadPriority" or
"SetThreadPriorityToRealtime"?

+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PlatformThread);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_PLATFORM_THREAD_H_