[mojo-edk] Add MojoWatch and MojoCancelWatch APIs

mojo/edk/system/data_pipe_producer_dispatcher.h

Index: mojo/edk/system/data_pipe_producer_dispatcher.h
diff --git a/mojo/edk/system/data_pipe_producer_dispatcher.h b/mojo/edk/system/data_pipe_producer_dispatcher.h
index c1020b0f5b560ec0ddc1f320c1a8d1867169ba80..2af81b830b84b05ef58327c4dcad8ee09d986084 100644
--- a/mojo/edk/system/data_pipe_producer_dispatcher.h
+++ b/mojo/edk/system/data_pipe_producer_dispatcher.h
@@ -41,7 +41,7 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeProducerDispatcher final
 
   // Dispatcher:
   Type GetType() const override;
-  MojoResult Close() override;
+  MojoResult Close(RequestContext* request_context) override;
   MojoResult WriteData(const void* elements,
                        uint32_t* num_bytes,
                        MojoReadDataFlags flags) override;
@@ -62,9 +62,9 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeProducerDispatcher final
   bool EndSerialize(void* destination,
                     ports::PortName* ports,
                     PlatformHandle* handles) override;
-  bool BeginTransit() override;
-  void CompleteTransitAndClose() override;
-  void CancelTransit() override;
+  bool BeginTransit(RequestContext* request_context) override;
+  void CompleteTransitAndClose(RequestContext* request_context) override;
+  void CancelTransit(RequestContext* request_context) override;
 
   static scoped_refptr<DataPipeProducerDispatcher>
   Deserialize(const void* data,