Move Thread Name Mapping into ThreadFunc.

base/threading/platform_thread_win.cc

Index: base/threading/platform_thread_win.cc
diff --git a/base/threading/platform_thread_win.cc b/base/threading/platform_thread_win.cc
index 9e877b32f9e1e630ce31c164f5e58680b898e5f7..b47f2b38f6b5e6946fb2e5ec6bf99d648396e1d9 100644
--- a/base/threading/platform_thread_win.cc
+++ b/base/threading/platform_thread_win.cc
@@ -46,6 +46,7 @@ void SetNameInternal(PlatformThreadId thread_id, const char* name) {
 struct ThreadParams {
   PlatformThread::Delegate* delegate;
   bool joinable;
+  PlatformThreadHandle* thread_handle;
 };
 
 DWORD __stdcall ThreadFunc(void* params) {
@@ -53,6 +54,10 @@ DWORD __stdcall ThreadFunc(void* params) {
   PlatformThread::Delegate* delegate = thread_params->delegate;
   if (!thread_params->joinable)
     base::ThreadRestrictions::SetSingletonAllowed(false);
+
+  ThreadIdNameManager::GetInstance()->RegisterThread(
+      thread_params->thread_handle,
+      PlatformThread::CurrentId());
   delete thread_params;
   delegate->ThreadMain();
   return NULL;

[jar (doing other things), 2013/05/22 19:37:56]

Wouldn't this be a great place to unregister, just in front of line 63?  ...
while the thread is still active... but about to terminate.... so it would be a
bad thing for folks to refer to us anyway IMO.

[Same thing in platform_thread_posix.cc]

[dsinclair, 2013/05/22 20:22:31]

The benefit I see from having it in the Join method of PlatformThread is that we
know all posted tasks are done. My concern was that, things like
MessageLoop::PostTask, use the thread name when they do TRACE_EVENT calls.

[jar (doing other things), 2013/05/22 21:36:48]

I think that by the time you hit line 63, any message loop on this thread should
be gone... so the question is: Who can/should be referencing the thread, and
asking questions about it?  Surely we won't be askin' any more questions
(tracing any more calls), as we're exiting here.

[dsinclair, 2013/05/23 18:21:53]

Done.

@@ -75,6 +80,7 @@ bool CreateThreadInternal(size_t stack_size,
   ThreadParams* params = new ThreadParams;
   params->delegate = delegate;
   params->joinable = out_thread_handle != NULL;
+  params->thread_handle = out_thread_handle;
 
   // Using CreateThread here vs _beginthreadex makes thread creation a bit
   // faster and doesn't require the loader lock to be available.  Our code will