contracts-bedrock: L2ToL1MessagePasser event extension

Emit an additional event during `initiateWithdrawal` that includes
the withdrawal hash so that it is easy to observe changes to the
`sentMessages` mapping.

.changeset/hip-shrimps-cheat.md

+---
+'@eth-optimism/contracts-bedrock': patch
+---
+
+Emit an extra event when withdrawals are initiated to make chainops easier

packages/contracts-bedrock/.gas-snapshot

@@ -69,8 +69,8 @@ L2CrossDomainMessenger_Test:test_L2MessengerRelayMessageFirstStuckSecondSucceeds
 L2CrossDomainMessenger_Test:test_L2MessengerRelayMessageSucceeds() (gas: 57396)
 L2CrossDomainMessenger_Test:test_L2MessengerRelayMessageToSystemContract() (gas: 36217)
 L2CrossDomainMessenger_Test:test_L2MessengerRelayShouldRevertIfPaused() (gas: 41682)
-L2CrossDomainMessenger_Test:test_L2MessengerSendMessage() (gas: 121684)
-L2CrossDomainMessenger_Test:test_L2MessengerTwiceSendMessage() (gas: 136258)
+L2CrossDomainMessenger_Test:test_L2MessengerSendMessage() (gas: 122833)
+L2CrossDomainMessenger_Test:test_L2MessengerTwiceSendMessage() (gas: 138556)
 L2CrossDomainMessenger_Test:test_L2MessengerXDomainSenderReverts() (gas: 10598)
 L2CrossDomainMessenger_Test:test_L2MessengerxDomainMessageSenderResets() (gas: 54889)
 L2OutputOracleTest:testCannot_ProposeWithUnmatchedBlockhash() (gas: 26829)
@@ -96,19 +96,19 @@ L2OutputOracleUpgradeable_Test:test_cannotInitImpl() (gas: 19555)
 L2OutputOracleUpgradeable_Test:test_cannotInitProxy() (gas: 24554)
 L2OutputOracleUpgradeable_Test:test_initValuesOnProxy() (gas: 39086)
 L2OutputOracleUpgradeable_Test:test_upgrading() (gas: 180632)
-L2StandardBridge_Test:test_ERC20BridgeFailed_whenLocalTokenIsBridge() (gas: 134358)
+L2StandardBridge_Test:test_ERC20BridgeFailed_whenLocalTokenIsBridge() (gas: 135507)
 L2StandardBridge_Test:test_cannotWithdrawEthWithoutSendingIt() (gas: 21619)
-L2StandardBridge_Test:test_finalizeBridgeERC20FailSendBack() (gas: 499449)
+L2StandardBridge_Test:test_finalizeBridgeERC20FailSendBack() (gas: 500368)
 L2StandardBridge_Test:test_finalizeDeposit() (gas: 93125)
-L2StandardBridge_Test:test_finalizeDeposit_failsToCompleteOutboundTransfer() (gas: 141373)
+L2StandardBridge_Test:test_finalizeDeposit_failsToCompleteOutboundTransfer() (gas: 142522)
 L2StandardBridge_Test:test_initialize() (gas: 14823)
-L2StandardBridge_Test:test_receive() (gas: 137921)
-L2StandardBridge_Test:test_withdraw() (gas: 353438)
-L2StandardBridge_Test:test_withdrawTo() (gas: 354193)
+L2StandardBridge_Test:test_receive() (gas: 139070)
+L2StandardBridge_Test:test_withdraw() (gas: 354357)
+L2StandardBridge_Test:test_withdrawTo() (gas: 355112)
 L2StandardBridge_Test:test_withdraw_onlyEOA() (gas: 251674)
-L2ToL1MessagePasserTest:test_burn() (gas: 112246)
-L2ToL1MessagePasserTest:test_initiateWithdrawal_fromContract() (gas: 68198)
-L2ToL1MessagePasserTest:test_initiateWithdrawal_fromEOA() (gas: 75284)
+L2ToL1MessagePasserTest:test_burn() (gas: 113395)
+L2ToL1MessagePasserTest:test_initiateWithdrawal_fromContract() (gas: 72486)
+L2ToL1MessagePasserTest:test_initiateWithdrawal_fromEOA() (gas: 76433)
 LegacyERC20ETH_Test:test_approve() (gas: 10796)
 LegacyERC20ETH_Test:test_burn() (gas: 10681)
 LegacyERC20ETH_Test:test_crossDomain() (gas: 10577)
@@ -279,4 +279,4 @@ SequencerFeeVault_Test:test_constructor() (gas: 7678)
 SequencerFeeVault_Test:test_minWithdrawalAmount() (gas: 5440)
 SequencerFeeVault_Test:test_receive() (gas: 17338)
 SequencerFeeVault_Test:test_revertWithdraw() (gas: 9342)
-SequencerFeeVault_Test:test_withdraw() (gas: 148784)
+SequencerFeeVault_Test:test_withdraw() (gas: 149933)

packages/contracts-bedrock/contracts/L2/L2ToL1MessagePasser.sol

@@ -49,6 +49,14 @@ contract L2ToL1MessagePasser is Semver {
         bytes data
     );
 
+    /**
+     * @notice Emitted any time a withdrawal is initiated. An extension to
+     *         WithdrawalInitiated so that the interface is maintained.
+     *
+     * @param hash The hash of the withdrawal
+     */
+    event WithdrawalInitiatedExtension1(bytes32 indexed hash);
+
     /**
      * @notice Emitted when the balance of this contract is burned.
      *
@@ -106,6 +114,8 @@ contract L2ToL1MessagePasser is Semver {
         sentMessages[withdrawalHash] = true;
 
         emit WithdrawalInitiated(nonce, msg.sender, _target, msg.value, _gasLimit, _data);
+        emit WithdrawalInitiatedExtension1(withdrawalHash);
+
         unchecked {
             ++nonce;
         }

packages/contracts-bedrock/contracts/test/L2ToL1MessagePasser.t.sol

@@ -18,6 +18,8 @@ contract L2ToL1MessagePasserTest is CommonTest {
         bytes data
     );
 
+    event WithdrawalInitiatedExtension1(bytes32 indexed hash);
+
     event WithdrawerBalanceBurnt(uint256 indexed amount);
 
     function setUp() virtual public {
@@ -36,6 +38,20 @@ contract L2ToL1MessagePasserTest is CommonTest {
             hex""
         );
 
+        bytes32 withdrawalHash = Hashing.hashWithdrawal(
+            Types.WithdrawalTransaction(
+                messagePasser.nonce(),
+                address(this),
+                address(4),
+                100,
+                64000,
+                hex""
+            )
+        );
+
+        vm.expectEmit(true, true, true, true);
+        emit WithdrawalInitiatedExtension1(withdrawalHash);
+
         vm.deal(address(this), 2**64);
         messagePasser.initiateWithdrawal{ value: 100 }(
             address(4),