base::Bind: Make use of partial currying to get rid of a helper class.

base/callback.h.pump

Index: base/callback.h.pump
diff --git a/base/callback.h.pump b/base/callback.h.pump
index 82660f335e599559b9fead2b72f6646ddd0a90d4..882cae902781aac210df2dd087ad3504b78e5b94 100644
--- a/base/callback.h.pump
+++ b/base/callback.h.pump
@@ -129,7 +129,7 @@ $var MAX_ARITY = 7
 // There are three main components to the system:
 //   1) The Callback classes.
 //   2) The Bind() functions.
-//   3) The arguments wrappers (eg., Unretained() and ConstRef()).
+//   3) The arguments wrappers (e.g., Unretained() and ConstRef()).
 //
 // The Callback classes represent a generic function pointer. Internally,
 // it stores a refcounted piece of state that represents the target function
@@ -165,7 +165,7 @@ $var MAX_ARITY = 7
 // to refcount a target object if the function being bound is a class method.
 //
 // To change this behavior, we introduce a set of argument wrappers
-// (eg. Unretained(), and ConstRef()).  These are simple container templates
+// (e.g., Unretained(), and ConstRef()).  These are simple container templates
 // that are passed by value, and wrap a pointer to argument.  See the
 // file-level comment in base/bind_helpers.h for more info.
 //
@@ -202,7 +202,7 @@ $var MAX_ARITY = 7
 // Lastly, tr1::function and tr1::bind has a more general and flexible API.
 // This includes things like argument reordering by use of
 // tr1::bind::placeholder, support for non-const reference parameters, and some
-// limited amount of subtyping of the tr1::function object (eg.,
+// limited amount of subtyping of the tr1::function object (e.g.,
 // tr1::function<int(int)> is convertible to tr1::function<void(int)>).
 //
 // These are not features that are required in Chromium. Some of them, such as