Mojo: add support for disallowing sync calls for a process.

mojo/public/c/system/functions.h

Index: mojo/public/c/system/functions.h
diff --git a/mojo/public/c/system/functions.h b/mojo/public/c/system/functions.h
index bd4daedaf7bbcae173861adfa171c6efe677d739..f0a23d931dee03583dc464afb4b2b7dd4ef9d2a1 100644
--- a/mojo/public/c/system/functions.h
+++ b/mojo/public/c/system/functions.h
@@ -206,6 +206,16 @@ MojoWatch(MojoHandle handle,
 MOJO_SYSTEM_EXPORT MojoResult
 MojoCancelWatch(MojoHandle handle, uintptr_t context);
 
+// Retrieves system properties. See the documentation for |MojoPropertyType| for
+// supported property types and their corresponding output value type.
+//
+// Returns:
+//     |MOJO_RESULT_OK| on success.
+//     |MOJO_RESULT_INVALID_ARGUMENT| if |type| is not recognized. In this case,
+//         |value| is untouched.
+MOJO_SYSTEM_EXPORT MojoResult MojoGetProperty(MojoPropertyType type,
+                                              void* value);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif