Add onSignaturesCollected

contracts/upgradeable_contracts/BasicHomeBridge.sol

@@ -78,10 +78,7 @@ contract BasicHomeBridge is EternalStorage, Validatable, Ownable, OwnedUpgradeab
             setNumMessagesSigned(hashMsg, markAsProcessed(signed));
             emit CollectedSignatures(msg.sender, hashMsg, reqSigs);
 
-            address feeManager = feeManagerContract();
-            if (feeManager != address(0)) {
-                handleSignatureFeeDistribution(feeManager, message);
-            }
+            onSignaturesCollected(message);
         }
     }
 
@@ -102,6 +99,9 @@ contract BasicHomeBridge is EternalStorage, Validatable, Ownable, OwnedUpgradeab
     function onExecuteAffirmation(address, uint256) internal returns(bool) {
     }
 
+    function onSignaturesCollected(bytes) internal {
+    }
+
     function numAffirmationsSigned(bytes32 _withdrawal) public view returns(uint256) {
         return uintStorage[keccak256(abi.encodePacked("numAffirmationsSigned", _withdrawal))];
     }

contracts/upgradeable_contracts/erc20_to_native/HomeBridgeErcToNative.sol

@@ -102,6 +102,13 @@ contract HomeBridgeErcToNative is EternalStorage, BasicBridge, BasicHomeBridge,
         return true;
     }
 
+    function onSignaturesCollected(bytes _message) internal {
+        address feeManager = feeManagerContract();
+        if (feeManager != address(0)) {
+            handleSignatureFeeDistribution(feeManager, _message);
+        }
+    }
+
     function fireEventOnTokenTransfer(address _from, uint256 _value) internal {
         emit UserRequestForSignature(_from, _value);
     }