wallet: move get_depending_transactions to AddressSynchronizer

and resolve TODO

electrum/address_synchronizer.py

@@ -319,6 +319,14 @@ class AddressSynchronizer(PrintError):
             self.txi.pop(tx_hash, None)
             self.txo.pop(tx_hash, None)
 
+    def get_depending_transactions(self, tx_hash):
+        """Returns all (grand-)children of tx_hash in this wallet."""
+        children = set()
+        for other_hash in self.spent_outpoints[tx_hash].values():
+            children.add(other_hash)
+            children |= self.get_depending_transactions(other_hash)
+        return children
+
     def receive_tx_callback(self, tx_hash, tx, tx_height):
         self.add_unverified_tx(tx_hash, tx_height)
         self.add_transaction(tx_hash, tx, allow_unrelated=True)

electrum/wallet.py

@@ -1068,17 +1068,6 @@ class Abstract_Wallet(AddressSynchronizer):
         index = self.get_address_index(addr)
         return self.keystore.decrypt_message(index, message, password)
 
-    def get_depending_transactions(self, tx_hash):
-        """Returns all (grand-)children of tx_hash in this wallet."""
-        children = set()
-        # TODO rewrite this to use self.spent_outpoints
-        for other_hash, tx in self.transactions.items():
-            for input in (tx.inputs()):
-                if input["prevout_hash"] == tx_hash:
-                    children.add(other_hash)
-                    children |= self.get_depending_transactions(other_hash)
-        return children
-
     def txin_value(self, txin):
         txid = txin['prevout_hash']
         prev_n = txin['prevout_n']