Revert of Deletes mojo::Callback

mojo/public/cpp/bindings/lib/router.h

Index: mojo/public/cpp/bindings/lib/router.h
diff --git a/mojo/public/cpp/bindings/lib/router.h b/mojo/public/cpp/bindings/lib/router.h
index 4515a7e783468a233639d3ceaa178d5ade8574f9..2f5e8e2a971366c0ddc04895635be9d0565b29e5 100644
--- a/mojo/public/cpp/bindings/lib/router.h
+++ b/mojo/public/cpp/bindings/lib/router.h
@@ -11,12 +11,12 @@
 #include <memory>
 #include <queue>
 
-#include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
+#include "mojo/public/cpp/bindings/callback.h"
 #include "mojo/public/cpp/bindings/lib/connector.h"
 #include "mojo/public/cpp/bindings/lib/filter_chain.h"
 
@@ -41,7 +41,7 @@
 
   // Sets the error handler to receive notifications when an error is
   // encountered while reading from the pipe or waiting to read from the pipe.
-  void set_connection_error_handler(const base::Closure& error_handler) {
+  void set_connection_error_handler(const Closure& error_handler) {
     error_handler_ = error_handler;
   }
 
@@ -166,7 +166,7 @@
   // |pending_messages_|.
   bool pending_task_for_messages_;
   bool encountered_error_;
-  base::Closure error_handler_;
+  Closure error_handler_;
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<Router> weak_factory_;
 };