refactor(erc20_to_native): rn _txHash into _nonce

contracts/upgradeable_contracts/MessageRelay.sol

@@ -3,11 +3,11 @@ pragma solidity 0.4.24;
 import "../upgradeability/EternalStorage.sol";
 
 contract MessageRelay is EternalStorage {
-    function relayedMessages(bytes32 _txHash) public view returns (bool) {
-        return boolStorage[keccak256(abi.encodePacked("relayedMessages", _txHash))];
+    function relayedMessages(bytes32 _nonce) public view returns (bool) {
+        return boolStorage[keccak256(abi.encodePacked("relayedMessages", _nonce))];
     }
 
-    function setRelayedMessages(bytes32 _txHash, bool _status) internal {
-        boolStorage[keccak256(abi.encodePacked("relayedMessages", _txHash))] = _status;
+    function setRelayedMessages(bytes32 _nonce, bool _status) internal {
+        boolStorage[keccak256(abi.encodePacked("relayedMessages", _nonce))] = _status;
     }
 }

contracts/upgradeable_contracts/RewardableBridge.sol

@@ -119,25 +119,25 @@ contract RewardableBridge is Ownable, FeeTypes {
      * @dev Internal function for distributing the fee for collecting sufficient amount of signatures.
      * @param _fee amount of fee to distribute.
      * @param _feeManager address of the fee manager contract.
-     * @param _txHash reference transaction hash where the original bridge request happened.
+     * @param _nonce reference to the nonce generated on the Foreign side.
      */
-    function distributeFeeFromSignatures(uint256 _fee, address _feeManager, bytes32 _txHash) internal {
+    function distributeFeeFromSignatures(uint256 _fee, address _feeManager, bytes32 _nonce) internal {
         if (_fee > 0) {
             require(_feeManager.delegatecall(abi.encodeWithSelector(DISTRIBUTE_FEE_FROM_SIGNATURES, _fee)));
-            emit FeeDistributedFromSignatures(_fee, _txHash);
+            emit FeeDistributedFromSignatures(_fee, _nonce);
         }
     }
 
     /**
      * @dev Internal function for distributing the fee for collecting sufficient amount of affirmations.
      * @param _fee amount of fee to distribute.
      * @param _feeManager address of the fee manager contract.
-     * @param _txHash reference transaction hash where the original bridge request happened.
+     * @param _nonce reference to the nonce generated on the Foreign side.
      */
-    function distributeFeeFromAffirmation(uint256 _fee, address _feeManager, bytes32 _txHash) internal {
+    function distributeFeeFromAffirmation(uint256 _fee, address _feeManager, bytes32 _nonce) internal {
         if (_fee > 0) {
             require(_feeManager.delegatecall(abi.encodeWithSelector(DISTRIBUTE_FEE_FROM_AFFIRMATION, _fee)));
-            emit FeeDistributedFromAffirmation(_fee, _txHash);
+            emit FeeDistributedFromAffirmation(_fee, _nonce);
         }
     }
 }

contracts/upgradeable_contracts/erc20_to_native/ForeignBridgeErcToNative.sol

@@ -51,7 +51,7 @@ contract ForeignBridgeErcToNative is ERC20Bridge, OtherSideBridgeStorage {
     function onExecuteMessage(
         address _recipient,
         uint256 _amount,
-        bytes32 /*_txHash*/
+        bytes32 /*_nonce*/
     ) internal returns (bool) {
         addTotalExecutedPerDay(getCurrentDay(), _amount);
         return erc20token().transfer(_recipient, _unshiftValue(_amount));

contracts/upgradeable_contracts/erc20_to_native/HomeBridgeErcToNative.sol

@@ -169,11 +169,11 @@ contract HomeBridgeErcToNative is
      * Should be called only after enough affirmations from the validators are already collected.
      * @param _recipient address of the receiver where the new coins should be minted.
      * @param _value amount of coins to mint.
-     * @param _txHash reference transaction hash on the Foreign side of the bridge which cause this operation.
+     * @param _nonce reference to the nonce generated on the Foreign side.
      * @param _hashMsg unique identifier of the particular bridge operation.
      * @return true, if execution completed successfully.
      */
-    function onExecuteAffirmation(address _recipient, uint256 _value, bytes32 _txHash, bytes32 _hashMsg)
+    function onExecuteAffirmation(address _recipient, uint256 _value, bytes32 _nonce, bytes32 _hashMsg)
         internal
         returns (bool)
     {
@@ -185,7 +185,7 @@ contract HomeBridgeErcToNative is
         address feeManager = feeManagerContract();
         if (feeManager != address(0)) {
             uint256 fee = calculateFee(valueToMint, false, feeManager, FOREIGN_FEE);
-            distributeFeeFromAffirmation(fee, feeManager, _txHash);
+            distributeFeeFromAffirmation(fee, feeManager, _nonce);
             valueToMint = valueToMint.sub(fee);
         }
         blockReward.addExtraReceiver(valueToMint, _recipient);
@@ -215,14 +215,14 @@ contract HomeBridgeErcToNative is
      * This function saves the bridge operation information for further processing.
      * @param _recipient address of the receiver where the new coins should be minted.
      * @param _value amount of coins to mint.
-     * @param _txHash reference transaction hash on the Foreign side of the bridge which cause this operation.
+     * @param _nonce reference to the nonce generated on the Foreign side.
      * @param _hashMsg unique identifier of the particular bridge operation.
      */
-    function onFailedAffirmation(address _recipient, uint256 _value, bytes32 _txHash, bytes32 _hashMsg) internal {
+    function onFailedAffirmation(address _recipient, uint256 _value, bytes32 _nonce, bytes32 _hashMsg) internal {
         (address recipient, uint256 value) = txAboveLimits(_hashMsg);
         require(recipient == address(0) && value == 0);
         setOutOfLimitAmount(outOfLimitAmount().add(_value));
         setTxAboveLimits(_recipient, _value, _hashMsg);
-        emit AmountLimitExceeded(_recipient, _value, _txHash, _hashMsg);
+        emit AmountLimitExceeded(_recipient, _value, _nonce, _hashMsg);
     }
 }

contracts/upgradeable_contracts/erc20_to_native/XDaiForeignBridge.sol

@@ -80,7 +80,7 @@ contract XDaiForeignBridge is ForeignBridgeErcToNative, SavingsDaiConnector, GSN
     function onExecuteMessage(
         address _recipient,
         uint256 _amount,
-        bytes32 /*_txHash*/
+        bytes32 /*_nonce*/
     ) internal returns (bool) {
         addTotalExecutedPerDay(getCurrentDay(), _amount);
 

test/foundry/interfaces/IXDaiForeignBridge.sol

@@ -61,7 +61,7 @@ interface IXDaiForeignBridge {
     function previewWithdraw(address _token, uint256 _amount) external view returns (uint256);
     function refillBridge() external;
     function relayTokens(address _receiver, uint256 _amount) external;
-    function relayedMessages(bytes32 _txHash) external view returns (bool);
+    function relayedMessages(bytes32 _nonce) external view returns (bool);
     function requiredBlockConfirmations() external view returns (uint256);
     function requiredSignatures() external view returns (uint256);
     function sDaiToken() external pure returns (address);