Clean up base::Callback stuff

base/callback_internal.h

Index: base/callback_internal.h
diff --git a/base/callback_internal.h b/base/callback_internal.h
index aa8542cf48f9b316e4cc1b4c7963b431b81ed584..2f6e22c2cd1b343b7c77ec5919ccec1592d8394c 100644
--- a/base/callback_internal.h
+++ b/base/callback_internal.h
@@ -67,6 +67,9 @@ class BASE_EXPORT CallbackBase {
   // Returns the Callback into an uninitialized state.
   void Reset();
 
+  // Returns true if this callback equals |other|. |other| may be null.
+  bool Equals(const CallbackBase& other) const;

[dcheng, 2015/12/08 20:16:46]

I'm curious: do you know why we didn't just do this to begin with?

[danakj, 2015/12/08 22:12:59]

Does this allow comparison of

Callback<void(int)> and Callback<void(int, int)> to compile because they both
upcast to CallbackBase?

[tzik, 2015/12/09 07:03:15]

Ah, yes. Let me revert this part, that is an unintended side effect of the clean
up.

+
  protected:
   // In C++, it is safe to cast function pointers to function pointers of
   // another type. It is not okay to use void*. We create a InvokeFuncStorage
@@ -74,9 +77,6 @@ class BASE_EXPORT CallbackBase {
   // the original type on usage.
   typedef void(*InvokeFuncStorage)(void);
 
-  // Returns true if this callback equals |other|. |other| may be null.
-  bool Equals(const CallbackBase& other) const;
-
   // Allow initializing of |bind_state_| via the constructor to avoid default
   // initialization of the scoped_refptr.  We do not also initialize
   // |polymorphic_invoke_| here because doing a normal assignment in the