Introduce PlatformThread::Detach

base/threading/platform_thread.h

Index: base/threading/platform_thread.h
diff --git a/base/threading/platform_thread.h b/base/threading/platform_thread.h
index 72da93bf56d4fc984c35c5f49ef2a69fd475be00..765f3b367c215d65116413f91be0f5f3eebd3751 100644
--- a/base/threading/platform_thread.h
+++ b/base/threading/platform_thread.h
@@ -180,6 +180,10 @@ class BASE_EXPORT PlatformThread {
   // |thread_handle|.
   static void Join(PlatformThreadHandle thread_handle);
 
+  // Detaches and releases the thread handle. The thread is no longer joinable
+  // after this call.

[danakj, 2016/06/09 22:58:07]

And the PlatformThreadHandle becomes invalid?

On windows this has no effect if the thread is the current thread. What happens
on posix? Do we want to support this?

[robliao, 2016/06/10 14:24:31]

Yup, the PlatformThreadHandle becomes invalid. Updated comment.

I think what you mean is Windows is okay if the handle represents the current
thread. Yes, as handles apply to the entire process. POSIX doesn't seem to mind
either (return value 0). Since the underlying platforms support it, I think it's
fine if we support it as well. I don't see a reason why not.

+  static void Detach(PlatformThreadHandle thread_handle);
+
   // Toggles the current thread's priority at runtime. A thread may not be able
   // to raise its priority back up after lowering it if the process does not
   // have a proper permission, e.g. CAP_SYS_NICE on Linux. A thread may not be