Cleanup: Remove internal two-phase data pipe all-or-none support.

mojo/edk/system/data_pipe.h

Index: mojo/edk/system/data_pipe.h
diff --git a/mojo/edk/system/data_pipe.h b/mojo/edk/system/data_pipe.h
index c5a1c645225be4c0990cc996b2de543c97c8d4eb..180c981032603e5a5154acc66362217ca94dd062 100644
--- a/mojo/edk/system/data_pipe.h
+++ b/mojo/edk/system/data_pipe.h
@@ -107,8 +107,7 @@ class DataPipe final : public ChannelEndpointClient {
                                UserPointer<uint32_t> num_bytes,
                                bool all_or_none);
   MojoResult ProducerBeginWriteData(UserPointer<void*> buffer,
-                                    UserPointer<uint32_t> buffer_num_bytes,
-                                    bool all_or_none);
+                                    UserPointer<uint32_t> buffer_num_bytes);
   MojoResult ProducerEndWriteData(uint32_t num_bytes_written);
   HandleSignalsState ProducerGetHandleSignalsState();
   MojoResult ProducerAddAwakable(Awakable* awakable,
@@ -140,8 +139,7 @@ class DataPipe final : public ChannelEndpointClient {
                                  bool all_or_none);
   MojoResult ConsumerQueryData(UserPointer<uint32_t> num_bytes);
   MojoResult ConsumerBeginReadData(UserPointer<const void*> buffer,
-                                   UserPointer<uint32_t> buffer_num_bytes,
-                                   bool all_or_none);
+                                   UserPointer<uint32_t> buffer_num_bytes);
   MojoResult ConsumerEndReadData(uint32_t num_bytes_read);
   HandleSignalsState ConsumerGetHandleSignalsState();
   MojoResult ConsumerAddAwakable(Awakable* awakable,