Remove use of IsRBFOptIn in wallet code

This commit does not change behavior.

src/interfaces/chain.cpp

@@ -6,9 +6,11 @@
 
 #include <chain.h>
 #include <chainparams.h>
+#include <policy/rbf.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <threadsafety.h>
+#include <txmempool.h>
 #include <uint256.h>
 #include <util/system.h>
 #include <validation.h>
@@ -183,6 +185,11 @@ public:
         LOCK(cs_main);
         return GuessVerificationProgress(Params().TxData(), LookupBlockIndex(block_hash));
     }
+    RBFTransactionState isRBFOptIn(const CTransaction& tx) override
+    {
+        LOCK(::mempool.cs);
+        return IsRBFOptIn(tx, ::mempool);
+    }
 };
 
 } // namespace

src/interfaces/chain.h

@@ -5,7 +5,8 @@
 #ifndef BITCOIN_INTERFACES_CHAIN_H
 #define BITCOIN_INTERFACES_CHAIN_H
 
-#include <optional.h>
+#include <optional.h>               // For Optional and nullopt
+#include <policy/rbf.h>             // For RBFTransactionState
 
 #include <memory>
 #include <stdint.h>
@@ -131,6 +132,9 @@ public:
     //! Estimate fraction of total transactions verified if blocks up to
     //! the specified block hash are verified.
     virtual double guessVerificationProgress(const uint256& block_hash) = 0;
+
+    //! Check if transaction is RBF opt in.
+    virtual RBFTransactionState isRBFOptIn(const CTransaction& tx) = 0;
 };
 
 //! Interface to let node manage chain clients (wallets, or maybe tools for