Revert of Deletes mojo::Callback

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

Index: mojo/public/cpp/bindings/lib/interface_endpoint_client.h
diff --git a/mojo/public/cpp/bindings/lib/interface_endpoint_client.h b/mojo/public/cpp/bindings/lib/interface_endpoint_client.h
index 8c72ff12cb2c2d4029f71f153859b8c51943052c..3f820db3c30c66b179e6b2203478f66bb0b19509 100644
--- a/mojo/public/cpp/bindings/lib/interface_endpoint_client.h
+++ b/mojo/public/cpp/bindings/lib/interface_endpoint_client.h
@@ -10,13 +10,13 @@
 #include <map>
 #include <memory>
 
-#include "base/callback.h"
 #include "base/logging.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/message.h"
 #include "mojo/public/cpp/bindings/message_filter.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
@@ -46,7 +46,7 @@
 
   // Sets the error handler to receive notifications when an error is
   // encountered.
-  void set_connection_error_handler(const base::Closure& error_handler) {
+  void set_connection_error_handler(const Closure& error_handler) {
     DCHECK(thread_checker_.CalledOnValidThread());
     error_handler_ = error_handler;
   }
@@ -139,7 +139,7 @@
 
   uint64_t next_request_id_;
 
-  base::Closure error_handler_;
+  Closure error_handler_;
   bool encountered_error_;
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;