Add Dispatcher methods for wait sets.

mojo/edk/system/entrypoint_class.h

Index: mojo/edk/system/entrypoint_class.h
diff --git a/mojo/edk/system/entrypoint_class.h b/mojo/edk/system/entrypoint_class.h
index d6828a96fdb7fcaa11cb76d17c58c69222da2497..236655879283f558861a723238bd3c7232c1f94e 100644
--- a/mojo/edk/system/entrypoint_class.h
+++ b/mojo/edk/system/entrypoint_class.h
@@ -36,6 +36,10 @@ enum class EntrypointClass {
   // |Dispatcher::DuplicateBufferHandle()|,
   // |Dispatcher::GetBufferInformation()|, |Dispatcher::MapBuffer()|:
   BUFFER,
+
+  // |Dispatcher::WaitSetAdd()|, |Dispatcher::WaitSetRemove()|,
+  // |Dispatcher::WaitSetWait()|:
+  WAIT_SET,
 };
 
 }  // namespace system