Annotate ThreadData::PushToHeadOfList for MemorySanitizer.

base/tracked_objects.cc

Index: base/tracked_objects.cc
diff --git a/base/tracked_objects.cc b/base/tracked_objects.cc
index b3bc975374275e56ee40fc6959fea3d6b29fc8c7..76d6cccdeaa4b30e315f4b194a4a7f2f2678a3c3 100644
--- a/base/tracked_objects.cc
+++ b/base/tracked_objects.cc
@@ -7,6 +7,7 @@
 #include <math.h>
 #include <stdlib.h>
 
+#include "base/compiler_specific.h"
 #include "base/format_macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/process_util.h"
@@ -258,6 +259,7 @@ void ThreadData::PushToHeadOfList() {
   // Toss in a hint of randomness (atop the uniniitalized value).
   (void)VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE(&random_number_,
                                                  sizeof(random_number_));
+  MSAN_UNPOISON(&random_number_, sizeof(random_number_));
   random_number_ += static_cast<int32>(this - static_cast<ThreadData*>(0));
   random_number_ ^= (Now() - TrackedTime()).InMilliseconds();