Convert //sandbox to use std::unique_ptr

sandbox/mac/mach_message_server.h

Index: sandbox/mac/mach_message_server.h
diff --git a/sandbox/mac/mach_message_server.h b/sandbox/mac/mach_message_server.h
index 515d56551395caf388a3bfa6a1cda6db519957dc..ace30ec97a753cb5bebe1cbe39ac72739f62b6ca 100644
--- a/sandbox/mac/mach_message_server.h
+++ b/sandbox/mac/mach_message_server.h
@@ -8,10 +8,11 @@
 #include <mach/mach.h>
 #include <stddef.h>
 
+#include <memory>
+
 #include "base/mac/dispatch_source_mach.h"
 #include "base/mac/scoped_mach_port.h"
 #include "base/mac/scoped_mach_vm.h"
-#include "base/memory/scoped_ptr.h"
 #include "sandbox/mac/message_server.h"
 
 namespace sandbox {
@@ -63,7 +64,7 @@ class MachMessageServer : public MessageServer {
   base::mac::ScopedMachVM reply_buffer_;
 
   // MACH_RECV dispatch source that handles the |server_port_|.
-  scoped_ptr<base::DispatchSourceMach> dispatch_source_;
+  std::unique_ptr<base::DispatchSourceMach> dispatch_source_;
 
   // Whether or not ForwardMessage() was called during ReceiveMessage().
   bool did_forward_message_;