[mojo-edk] Add MojoWatch and MojoCancelWatch APIs

mojo/edk/system/wait_set_dispatcher.h

Index: mojo/edk/system/wait_set_dispatcher.h
diff --git a/mojo/edk/system/wait_set_dispatcher.h b/mojo/edk/system/wait_set_dispatcher.h
index 11e82cdf04d89943e0e2b846c128db3e683aeb0f..092e59540e3b13ebe8d31a5cb64a31059a0cb6f7 100644
--- a/mojo/edk/system/wait_set_dispatcher.h
+++ b/mojo/edk/system/wait_set_dispatcher.h
@@ -27,7 +27,7 @@ class MOJO_SYSTEM_IMPL_EXPORT WaitSetDispatcher : public Dispatcher {
 
   // Dispatcher:
   Type GetType() const override;
-  MojoResult Close() override;
+  MojoResult Close(RequestContext* request_context) override;
   MojoResult AddWaitingDispatcher(const scoped_refptr<Dispatcher>& dispatcher,
                                   MojoHandleSignals signals,
                                   uintptr_t context) override;
@@ -44,7 +44,7 @@ class MOJO_SYSTEM_IMPL_EXPORT WaitSetDispatcher : public Dispatcher {
                          HandleSignalsState* signals_state) override;
   void RemoveAwakable(Awakable* awakable,
                       HandleSignalsState* signals_state) override;
-  bool BeginTransit() override;
+  bool BeginTransit(RequestContext* request_context) override;
 
  private:
   // Internal implementation of Awakable.