Add Darwin thread.h implementation.

webrtc/base/scoped_autorelease_pool.h

-/*
- *  Copyright 2008 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-// Automatically initialize and and free an autoreleasepool. Never allocate
-// an instance of this class using "new" - that will result in a compile-time
-// error. Only use it as a stack object.
-//
-// Note: NSAutoreleasePool docs say that you should not normally need to
-// declare an NSAutoreleasePool as a member of an object - but there's nothing
-// that indicates it will be a problem, as long as the stack lifetime of the
-// pool exactly matches the stack lifetime of the object.
-
-#ifndef WEBRTC_BASE_SCOPED_AUTORELEASE_POOL_H__
-#define WEBRTC_BASE_SCOPED_AUTORELEASE_POOL_H__
-
-#if defined(WEBRTC_MAC)
-
-#include "webrtc/base/constructormagic.h"
-
-// This header may be included from Obj-C files or C++ files.
-#ifdef __OBJC__
-@class NSAutoreleasePool;
-#else
-class NSAutoreleasePool;
-#endif
-
-namespace rtc {
-
-class ScopedAutoreleasePool {
- public:
-  ScopedAutoreleasePool();
-  ~ScopedAutoreleasePool();
-
- private:
-  // Declaring private overrides of new and delete here enforces the "only use
-  // as a stack object" discipline.
-  //
-  // Note: new is declared as "throw()" to get around a gcc warning about new
-  // returning null, but this method will never get called and therefore will
-  // never actually throw any exception.
-  void* operator new(size_t size) throw() { return nullptr; }
-  void operator delete (void* ptr) {}
-
-  NSAutoreleasePool* pool_;
-
-  RTC_DISALLOW_COPY_AND_ASSIGN(ScopedAutoreleasePool);
-};
-
-}  // namespace rtc
-
-#endif  // WEBRTC_MAC
-#endif  // WEBRTC_BASE_SCOPED_AUTORELEASE_POOL_H__