address review comments.

api/api_common.go

@@ -16,11 +16,6 @@ import (
 	"github.com/filecoin-project/lotus/build"
 )
 
-type ChainIO interface {
-	ChainReadObj(context.Context, cid.Cid) ([]byte, error)
-	ChainHasObj(context.Context, cid.Cid) (bool, error)
-}
-
 type Common interface {
 
 	// MethodGroup: Auth

api/api_full.go

@@ -32,6 +32,12 @@ import (
 	"github.com/filecoin-project/lotus/node/modules/dtypes"
 )
 
+// ChainIO abstracts operations for accessing raw IPLD objects.
+type ChainIO interface {
+	ChainReadObj(context.Context, cid.Cid) ([]byte, error)
+	ChainHasObj(context.Context, cid.Cid) (bool, error)
+}
+
 // FullNode API is a low-level interface to the Filecoin network full node
 type FullNode interface {
 	Common