Devirtualize base::BindState to save ~1% of Chrome's binary size (~1MB)

base/callback.h

Index: base/callback.h
diff --git a/base/callback.h b/base/callback.h
index 00669dd83d1c2dbb518134f0243fd5dbec104133..5be4c34800c76918f354dae934c0634a5b3cbf32 100644
--- a/base/callback.h
+++ b/base/callback.h
@@ -367,7 +367,7 @@ class Callback<R(Args...)> : public internal::CallbackBase {
  public:
   typedef R(RunType)(Args...);
 
-  Callback() : CallbackBase(NULL) { }
+  Callback() {}
 
   // Note that this constructor CANNOT be explicit, and that Bind() CANNOT
   // return the exact Callback<> type.  See base/bind.h for details.
@@ -393,7 +393,7 @@ class Callback<R(Args...)> : public internal::CallbackBase {
     PolymorphicInvoke f =
         reinterpret_cast<PolymorphicInvoke>(polymorphic_invoke_);
 
-    return f(bind_state_.get(), internal::CallbackForward(args)...);
+    return f(bind_state_, internal::CallbackForward(args)...);
   }
 
  private: