Remove deprecated base::Bind APIs (see issue #3140)

This CL removes the following deprecated APIs:

- base::Bind()
- base::Callback
- base::Closure
- base::CancelableCallback
- base::CancelableClosure

The behavior that these APIs provided is still available using the *Repeating*
variants. However, consider strongly whether using these variants is actually
necessary in your case or whether the *Once* variants will suffice: unless your
callback *objects* (note: not variables!) need to be called multiple times,
they most likely can and should be the Once variants.

This applies the same changes as https://crrev.com/6cc94b5339.

include/base/cef_callback_forward.h

@@ -48,15 +48,11 @@ class OnceCallback;
 template <typename Signature>
 class RepeatingCallback;
 
-template <typename Signature>
-using Callback = RepeatingCallback<Signature>;
-
 // Syntactic sugar to make OnceClosure<void()> and RepeatingClosure<void()>
 // easier to declare since they will be used in a lot of APIs with delayed
 // execution.
 using OnceClosure = OnceCallback<void()>;
 using RepeatingClosure = RepeatingCallback<void()>;
-using Closure = Callback<void()>;
 
 }  // namespace base