Revert of Remove mutex locks in SchemeRegistry

third_party/WebKit/Source/wtf/Threading.h

Index: third_party/WebKit/Source/wtf/Threading.h
diff --git a/third_party/WebKit/Source/wtf/Threading.h b/third_party/WebKit/Source/wtf/Threading.h
index f24b9c5efa2be0ebdd66513515fc13bef87abb23..ffe95e6ca2ed435983ff0e16f7bb671007cb767f 100644
--- a/third_party/WebKit/Source/wtf/Threading.h
+++ b/third_party/WebKit/Source/wtf/Threading.h
@@ -65,11 +65,11 @@
 WTF_EXPORT void lockAtomicallyInitializedStaticMutex();
 WTF_EXPORT void unlockAtomicallyInitializedStaticMutex();
 
-// Implementations of these functions are only defined when ENABLE(ASSERT), and
-// should only be used within ASSERT or DCHECK.
+#if ENABLE(ASSERT)
 WTF_EXPORT bool isAtomicallyInitializedStaticMutexLockHeld();
 WTF_EXPORT bool isBeforeThreadCreated();
 WTF_EXPORT void willCreateThread();
+#endif
 
 }  // namespace WTF