Add ability to retrieve a thread_name given a thread_id.

base/threading/platform_thread_mac.mm

Index: base/threading/platform_thread_mac.mm
diff --git a/base/threading/platform_thread_mac.mm b/base/threading/platform_thread_mac.mm
index 96c672023f915af3bf93929e7ed557cc6ba1020c..95e6fff58551d23c211f23a042b0173ba7782c09 100644
--- a/base/threading/platform_thread_mac.mm
+++ b/base/threading/platform_thread_mac.mm
@@ -12,6 +12,7 @@
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/threading/thread_id_name_manager.h"
 #include "base/threading/thread_local.h"
 #include "base/tracked_objects.h"
 
@@ -50,6 +51,8 @@ void PlatformThread::SetName(const char* name) {
   current_thread_name.Pointer()->Set(const_cast<char*>(name));
   tracked_objects::ThreadData::InitializeThreadContext(name);
 
+  ThreadIdNameManager::GetInstance()->SetNameForId(CurrentId(), name);
+
   // pthread_setname_np is only available in 10.6 or later, so test
   // for it at runtime.
   int (*dynamic_pthread_setname_np)(const char*);