Change g_native_tls_key to be 32-bit wide to match underlying type.

base/threading/thread_local_storage.cc

Index: base/threading/thread_local_storage.cc
diff --git a/base/threading/thread_local_storage.cc b/base/threading/thread_local_storage.cc
index e1749c467a8bf18bece7023df78304089e7b4130..4f4169fe71815f909beac197f09cecbf3185589f 100644
--- a/base/threading/thread_local_storage.cc
+++ b/base/threading/thread_local_storage.cc
@@ -18,7 +18,7 @@ namespace {
 // Chromium consumers.
 
 // g_native_tls_key is the one native TLS that we use.  It stores our table.
-base::subtle::AtomicWord g_native_tls_key =
+base::subtle::Atomic32 g_native_tls_key =
     PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES;
 
 // g_last_used_tls_key is the high-water-mark of allocated thread local storage.