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..48041a06a4f0ba8b3e44b1fc3e19ff748a46942c 100644
--- a/base/threading/platform_thread_mac.mm
+++ b/base/threading/platform_thread_mac.mm
@@ -12,18 +12,11 @@
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
-#include "base/threading/thread_local.h"
+#include "base/threading/thread_id_name_manager.h"
 #include "base/tracked_objects.h"
 
 namespace base {
 
-namespace {
-
-LazyInstance<ThreadLocalPointer<char> >::Leaky
-    current_thread_name = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
 // If Cocoa is to be used on more than one thread, it must know that the
 // application is multithreaded.  Since it's possible to enter Cocoa code
 // from threads created by pthread_thread_create, Cocoa won't necessarily
@@ -47,7 +40,7 @@ void InitThreading() {
 
 // static
 void PlatformThread::SetName(const char* name) {
-  current_thread_name.Pointer()->Set(const_cast<char*>(name));
+  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
   tracked_objects::ThreadData::InitializeThreadContext(name);
 
   // pthread_setname_np is only available in 10.6 or later, so test
@@ -67,11 +60,6 @@ void PlatformThread::SetName(const char* name) {
   dynamic_pthread_setname_np(shortened_name.c_str());
 }
 
-// static
-const char* PlatformThread::GetName() {
-  return current_thread_name.Pointer()->Get();
-}
-
 namespace {
 
 void SetPriorityNormal(mach_port_t mach_thread_id) {