Minimize uses of lazy initialization by adding explicit initialization functions.

src/lazy-instance.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 47 matching lines @@
 // providing your own trait:
 // Example usage:
 //   struct MyCreateTrait {
 //     static void Construct(MyClass* allocated_ptr) {
 //       new (allocated_ptr) MyClass(/* extra parameters... */);
 //     }
 //   };
 //   static LazyInstance<MyClass, MyCreateTrait>::type my_instance =
 //      LAZY_INSTANCE_INITIALIZER;
 //
-// WARNING: This implementation of LazyInstance is NOT thread-safe by default.
-// See ThreadSafeInitOnceTrait declared below for that.
+// WARNINGS:
+// - This implementation of LazyInstance is NOT THREAD-SAFE by default. See
+//   ThreadSafeInitOnceTrait declared below for that.
+// - Lazy initialization comes with a cost. Make sure that you don't use it on
+//   critical path. Consider adding your initialization code to a function
+//   which is explicitly called once.
 //
 // Notes for advanced users:
 // LazyInstance can actually be used in two different ways:
 //
 // - "Static mode" which is the default mode since it is the most efficient
 //   (no extra heap allocation). In this mode, the instance is statically
 //   allocated (stored in the global data section at compile time).
 //   The macro LAZY_STATIC_INSTANCE_INITIALIZER (= LAZY_INSTANCE_INITIALIZER)
 //   must be used to initialize static lazy instances.
 //
@@ skipping 159 matching lines @@
           typename InitOnceTrait = SingleThreadInitOnceTrait,
           typename DestroyTrait = LeakyInstanceTrait<T> >
 struct LazyDynamicInstance {
   typedef LazyInstanceImpl<T, DynamicallyAllocatedInstanceTrait<T>,
       CreateTrait, InitOnceTrait, DestroyTrait> type;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_LAZY_INSTANCE_H_