Mojo EDK: Circulate MojoArmWatcher outputs to avoid starvation

mojo/public/c/system/watcher.h

Index: mojo/public/c/system/watcher.h
diff --git a/mojo/public/c/system/watcher.h b/mojo/public/c/system/watcher.h
index f152c50a11cf91578d08a1bcd6649f8d0769410b..e32856b6d920d58b2e0fa121a5fb1fd683547e9c 100644
--- a/mojo/public/c/system/watcher.h
+++ b/mojo/public/c/system/watcher.h
@@ -167,8 +167,9 @@ MOJO_SYSTEM_EXPORT MojoResult MojoCancelWatch(MojoHandle watcher_handle,
 //       output buffers is written to |*num_ready_contexts| before returning.
 //
 //       If more than (input) |*num_ready_contexts| watch contexts were ready to
-//       notify, the subset presented in output buffers is arbitrary and
-//       implementation-defined.
+//       notify, the subset presented in output buffers is arbitrary, but the
+//       implementation makes a best effort to circulate the outputs across
+//       consecutive calls so that callers may reliably avoid handle starvation.
 MOJO_SYSTEM_EXPORT MojoResult
 MojoArmWatcher(MojoHandle watcher_handle,
                uint32_t* num_ready_contexts,