Add memcheck annotation and remove suppression.

base/tracked_objects.cc

Index: base/tracked_objects.cc
diff --git a/base/tracked_objects.cc b/base/tracked_objects.cc
index 19d4786ee782a656f53473b267d495544a4e43cd..8bbd07e35845af830964aa85130dfb832a79a781 100644
--- a/base/tracked_objects.cc
+++ b/base/tracked_objects.cc
@@ -9,6 +9,7 @@
 #include "base/format_macros.h"
 #include "base/message_loop.h"
 #include "base/stringprintf.h"
+#include "base/third_party/valgrind/memcheck.h"
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "base/port.h"
@@ -219,6 +220,8 @@ ThreadData::~ThreadData() {}
 
 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_));
   random_number_ += static_cast<int32>(this - static_cast<ThreadData*>(0));
   random_number_ ^= (Now() - TrackedTime()).InMilliseconds();