NaCl: create a separate namespace for Mojo handles.

mojo/edk/system/core.h

Index: mojo/edk/system/core.h
diff --git a/mojo/edk/system/core.h b/mojo/edk/system/core.h
index aadfb661ec241d6938165e1b716cae3fe1453eec..0c38008d7432fc4a452ac51107b5a145bffbf3eb 100644
--- a/mojo/edk/system/core.h
+++ b/mojo/edk/system/core.h
@@ -52,6 +52,15 @@ class MOJO_SYSTEM_IMPL_EXPORT Core {
   // invalid.
   scoped_refptr<Dispatcher> GetDispatcher(MojoHandle handle);
 
+  // Like |GetDispatcher()|, but also removes the handle from the handle table.
+  // On success, gets the dispatcher for a given handle (which should not be
+  // |MOJO_HANDLE_INVALID|) and removes it. (On failure, returns an appropriate
+  // result (and leaves |dispatcher| alone), namely
+  // |MOJO_RESULT_INVALID_ARGUMENT| if there's no dispatcher for the given
+  // handle or |MOJO_RESULT_BUSY| if the handle is marked as busy.)
+  MojoResult GetAndRemoveDispatcher(MojoHandle handle,
+                                    scoped_refptr<Dispatcher>* dispatcher);
+
   // Watches on the given handle for the given signals, calling |callback| when
   // a signal is satisfied or when all signals become unsatisfiable. |callback|
   // must satisfy stringent requirements -- see |Awakable::Awake()| in