GN: aix port along with linux_s390x, linux_ppc64 and linux_ppc64le support.

base/threading/platform_thread_posix.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 <errno.h>
 #include <pthread.h>
 #include <sched.h>
 #include <stddef.h>
@@ skipping 126 matching lines @@
   return syscall(__NR_gettid);
 #elif defined(OS_ANDROID)
   return gettid();
 #elif defined(OS_SOLARIS) || defined(OS_QNX)
   return pthread_self();
 #elif defined(OS_NACL) && defined(__GLIBC__)
   return pthread_self();
 #elif defined(OS_NACL) && !defined(__GLIBC__)
   // Pointers are 32-bits in NaCl.
   return reinterpret_cast<int32_t>(pthread_self());
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) && defined(OS_AIX)
+  return pthread_self();
+#elif defined(OS_POSIX) && !defined(OS_AIX)
   return reinterpret_cast<int64_t>(pthread_self());
 #endif
 }
 
 // static
 PlatformThreadRef PlatformThread::CurrentRef() {
   return PlatformThreadRef(pthread_self());
 }
 
 // static
@@ skipping 128 matching lines @@
     return ThreadPriority::NORMAL;
   }
 
   return internal::NiceValueToThreadPriority(nice_value);
 #endif  // !defined(OS_NACL)
 }
 
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace base