Revert "Track thread activities in order to diagnose hangs."

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>
 #include <stdint.h>
 #include <sys/resource.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 #include <memory>
 
-#include "base/debug/activity_tracker.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/threading/platform_thread_internal_posix.h"
 #include "base/threading/thread_id_name_manager.h"
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 
 #if defined(OS_LINUX)
 #include <sys/syscall.h>
 #endif
@@ skipping 174 matching lines @@
                                                    ThreadPriority priority) {
   PlatformThreadHandle unused;
 
   bool result = CreateThread(stack_size, false /* non-joinable thread */,
                              delegate, &unused, priority);
   return result;
 }
 
 // static
 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
-  // Record the event that this thread is blocking upon (for hang diagnosis).
-  base::debug::ScopedThreadJoinActivity thread_activity(&thread_handle);
-
   // Joining another thread may block the current thread for a long time, since
   // the thread referred to by |thread_handle| may still be running long-lived /
   // blocking tasks.
   base::ThreadRestrictions::AssertIOAllowed();
   CHECK_EQ(0, pthread_join(thread_handle.platform_handle(), NULL));
 }
 
 // static
 void PlatformThread::Detach(PlatformThreadHandle thread_handle) {
   CHECK_EQ(0, pthread_detach(thread_handle.platform_handle()));
@@ skipping 59 matching lines @@
     return ThreadPriority::NORMAL;
   }
 
   return internal::NiceValueToThreadPriority(nice_value);
 #endif  // !defined(OS_NACL)
 }
 
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace base