[mojo-edk] Add MojoWatch and MojoCancelWatch APIs

mojo/edk/system/data_pipe_consumer_dispatcher.h

Index: mojo/edk/system/data_pipe_consumer_dispatcher.h
diff --git a/mojo/edk/system/data_pipe_consumer_dispatcher.h b/mojo/edk/system/data_pipe_consumer_dispatcher.h
index c75833bbf85e7ec6ead0d961622452c9a4d96db1..945aa073eeac38f18ada48a608fa73ca4597df3c 100644
--- a/mojo/edk/system/data_pipe_consumer_dispatcher.h
+++ b/mojo/edk/system/data_pipe_consumer_dispatcher.h
@@ -43,6 +43,10 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeConsumerDispatcher final
   // Dispatcher:
   Type GetType() const override;
   MojoResult Close() override;
+  MojoResult Watch(MojoHandleSignals signals,
+                   const Watcher::WatchCallback& callback,
+                   uintptr_t context) override;
+  MojoResult CancelWatch(uintptr_t context) override;
   MojoResult ReadData(void* elements,
                       uint32_t* num_bytes,
                       MojoReadDataFlags flags) override;