Don't create redundant ThreadData for Worker Threads

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..7e03f91861e35d26feac43a434b1f88a4716e549 100644
--- a/base/threading/platform_thread.h
+++ b/base/threading/platform_thread.h
@@ -144,7 +144,7 @@ class BASE_EXPORT PlatformThread {
 
   // Sets the thread name visible to debuggers/tools. This has no effect
   // otherwise.

[jar (doing other things), 2016/04/20 04:34:51]

I suspect the code has changed, because it appears that contrary to this
comment, this call probably has a side-effect of creating the ThreadData
instance (among other things).  This comment should probably be changed... or
perhaps you should look at the history to see when these semantics were changed.

[Zhenyu Shan, 2016/05/04 23:33:02]

Done.

This change is introduced in https://codereview.chromium.org/8558003

-  static void SetName(const std::string& name);
+  static void SetName(const std::string& name, bool is_worker_thread = false);
 
   // Gets the thread name, if previously set by SetName.
   static const char* GetName();