Bug 749678 - 2/5 - add include guards to thread_helpers.h - r=ehsan

tools/profiler/thread_helper.h

@@ -38,6 +38,9 @@
 
 // Cross-platform lightweight thread local data wrappers
 
+#ifndef MOZ_THREAD_HELPER_H
+#define MOZ_THREAD_HELPER_H
+
 #if defined(XP_WIN)
   // This file will get included in any file that wants to add
   // a profiler mark. In order to not bring <windows.h> together
@@ -114,3 +117,4 @@ inline bool create(key* mykey) {
 
 }
  
+#endif // MOZ_THREAD_HELPER_H
\ No newline at end of file