Convert verification of options structs to use the new user pointer handling (see r285350).

mojo/system/message_pipe_dispatcher.h

Index: mojo/system/message_pipe_dispatcher.h
diff --git a/mojo/system/message_pipe_dispatcher.h b/mojo/system/message_pipe_dispatcher.h
index e59267a938f4c72e46214e61bcdfbe48abe0cd91..b06001c68cee8579a45c3aaaa043f20a807d556f 100644
--- a/mojo/system/message_pipe_dispatcher.h
+++ b/mojo/system/message_pipe_dispatcher.h
@@ -11,6 +11,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "mojo/system/dispatcher.h"
+#include "mojo/system/memory.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
@@ -37,7 +38,7 @@ class MOJO_SYSTEM_IMPL_EXPORT MessagePipeDispatcher : public Dispatcher {
   // |MojoCreateMessagePipeOptions| and will be entirely overwritten on success
   // (it may be partly overwritten on failure).
   static MojoResult ValidateCreateOptions(
-      const MojoCreateMessagePipeOptions* in_options,
+      UserPointer<const MojoCreateMessagePipeOptions> in_options,
       MojoCreateMessagePipeOptions* out_options);
 
   // Must be called before any other methods. (This method is not thread-safe.)