NaCl: create a separate namespace for Mojo handles.

nacl_bindings/mojo_syscall.h

Index: nacl_bindings/mojo_syscall.h
diff --git a/nacl_bindings/mojo_syscall.h b/nacl_bindings/mojo_syscall.h
index 700d1912161f8dc61923f0cad7dda516bbcf4c68..031fdf20ae9464a8b354149818c9d97fb7b53b3a 100644
--- a/nacl_bindings/mojo_syscall.h
+++ b/nacl_bindings/mojo_syscall.h
@@ -12,12 +12,7 @@
 // implementation of the Mojo system API outside the NaCl sandbox and allows
 // untrusted code to communicate with Mojo interfaces outside the sandbox or in
 // other processes.
-void InjectMojo(struct NaClApp* nap, MojoHandle handle);
-
-// Injects a NaClDesc for Mojo support. This provides the implementation of the
-// Mojo system API outside the NaCl sandbox.
-// TODO(teravest): Remove this once it is no longer called.
-void InjectMojo(struct NaClApp* nap);
+MojoResult InjectMojo(struct NaClApp* nap, MojoHandle handle);
 
 // Injects a "disabled" NaClDesc for Mojo support. This is to make debugging
 // more straightforward in the case where Mojo is not enabled for NaCl plugins.