Move autowrap from ThreadManager constructor to Thread::Current.

webrtc/base/thread_darwin.mm

Index: webrtc/base/thread_darwin.mm
diff --git a/webrtc/base/thread_darwin.mm b/webrtc/base/thread_darwin.mm
index 5bcc5c8c06b220a67baad5182789c7c1fe983e47..5f2227d839c0f58f8acadf5ad4a744c3e1d03a97 100644
--- a/webrtc/base/thread_darwin.mm
+++ b/webrtc/base/thread_darwin.mm
@@ -39,22 +39,13 @@ void InitCocoaMultiThreading() {
 namespace rtc {
 
 ThreadManager::ThreadManager() {
+  main_thread_ref_ = CurrentThreadRef();
   pthread_key_create(&key_, nullptr);
-#ifndef NO_MAIN_THREAD_WRAPPING
-  WrapCurrentThread();
-#endif
   // This is necessary to alert the cocoa runtime of the fact that
   // we are running in a multithreaded environment.
   InitCocoaMultiThreading();
 }
 
-ThreadManager::~ThreadManager() {
-  @autoreleasepool {
-    UnwrapCurrentThread();
-    pthread_key_delete(key_);
-  }
-}
-
 // static
 void* Thread::PreRun(void* pv) {
   ThreadInit* init = static_cast<ThreadInit*>(pv);