Minor perf and size optimization - don't do asserts in release build

base/memory/singleton.h

Index: base/memory/singleton.h
diff --git a/base/memory/singleton.h b/base/memory/singleton.h
index bc4684b0b8940acf87ca016341465764967a26ab..f82a37ec865da1a966cb3b3681d2d1edf4ba1427 100644
--- a/base/memory/singleton.h
+++ b/base/memory/singleton.h
@@ -213,8 +213,11 @@ class Singleton {
 
   // Return a pointer to the one true instance of the class.
   static Type* get() {
+#ifndef NDEBUG
+    // Avoid making TLS lookup on release builds.
     if (!Traits::kAllowedToAccessOnNonjoinableThread)
       base::ThreadRestrictions::AssertSingletonAllowed();
+#endif
 
     // Our AtomicWord doubles as a spinlock, where a value of
     // kBeingCreatedMarker means the spinlock is being held for creation.