Add ability to retrieve a thread_name given a thread_id.

base/threading/platform_thread_posix.cc

Index: base/threading/platform_thread_posix.cc
diff --git a/base/threading/platform_thread_posix.cc b/base/threading/platform_thread_posix.cc
index 444edc58a6268649115f2f1583bc7b56374d961d..a066278bdb83ad9ebb7600da339eb14eebaaab6c 100644
--- a/base/threading/platform_thread_posix.cc
+++ b/base/threading/platform_thread_posix.cc
@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/safe_strerror_posix.h"
+#include "base/threading/thread_id_name_manager.h"
 #include "base/threading/thread_local.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/tracked_objects.h"
@@ -200,6 +201,8 @@ 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);
+
   // On linux we can get the thread names to show up in the debugger by setting
   // the process name for the LWP.  We don't want to do this for the main
   // thread because that would rename the process, causing tools like killall
@@ -227,6 +230,8 @@ 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);
+
   // (This should be relatively simple to implement for the BSDs; I
   // just don't have one handy to test the code on.)
 }