contracts-bedrock: ERC721Bridge pausable

Enable pausability in the ERC721Bridge following the other bridges
that also received pausability.

packages/contracts-bedrock/scripts/ChainAssertions.sol

@@ -42,7 +42,7 @@ library ChainAssertions {
         checkL1StandardBridge({ _contracts: _prox, _isProxy: true });
         checkL2OutputOracle(_prox, _cfg, _l2OutputOracleStartingTimestamp, _l2OutputOracleStartingBlockNumber);
         checkOptimismMintableERC20Factory(_prox);
-        checkL1ERC721Bridge(_prox);
+        checkL1ERC721Bridge({ _contracts: _prox, _isProxy: true });
         checkOptimismPortal({ _contracts: _prox, _cfg: _cfg, _isProxy: true });
         checkProtocolVersions({ _contracts: _prox, _cfg: _cfg, _isProxy: true });
     }

packages/contracts-bedrock/scripts/Deploy.s.sol

@@ -690,7 +690,11 @@ contract Deploy is Deployer {
         // are always proxies.
         Types.ContractSet memory contracts = _proxiesUnstrict();
         contracts.L1ERC721Bridge = address(bridge);
-        ChainAssertions.checkL1ERC721Bridge(contracts);
+
+        ChainAssertions.checkL1ERC721Bridge({
+            _contracts: contracts,
+            _isProxy: false
+        });
 
         addr_ = address(bridge);
     }
@@ -811,17 +815,22 @@ contract Deploy is Deployer {
         ProxyAdmin proxyAdmin = ProxyAdmin(mustGetAddress("ProxyAdmin"));
         address l1ERC721BridgeProxy = mustGetAddress("L1ERC721BridgeProxy");
         address l1ERC721Bridge = mustGetAddress("L1ERC721Bridge");
+        address superchainConfigProxy = mustGetAddress("SuperchainConfigProxy");
 
-        _callViaSafe({
-            _target: address(proxyAdmin),
-            _data: abi.encodeCall(ProxyAdmin.upgrade, (payable(l1ERC721BridgeProxy), l1ERC721Bridge))
+        _upgradeAndCallViaSafe({
+            _proxy: payable(l1ERC721BridgeProxy),
+            _implementation: l1ERC721Bridge,
+            _innerCallData: abi.encodeCall(L1ERC721Bridge.initialize, (SuperchainConfig(superchainConfigProxy)))
         });
 
         L1ERC721Bridge bridge = L1ERC721Bridge(l1ERC721BridgeProxy);
         string memory version = bridge.version();
         console.log("L1ERC721Bridge version: %s", version);
 
-        ChainAssertions.checkL1ERC721Bridge(_proxies());
+        ChainAssertions.checkL1ERC721Bridge({
+            _contracts: _proxies(),
+            _isProxy: true
+        });
     }
 
     /// @notice Ininitialize the OptimismMintableERC20Factory

packages/contracts-bedrock/src/L1/L1ERC721Bridge.sol

@@ -8,6 +8,7 @@ import { ISemver } from "src/universal/ISemver.sol";
 import { Predeploys } from "src/libraries/Predeploys.sol";
 import { CrossDomainMessenger } from "src/universal/CrossDomainMessenger.sol";
 import { Constants } from "src/libraries/Constants.sol";
+import { SuperchainConfig } from "src/L1/SuperchainConfig.sol";
 
 /// @title L1ERC721Bridge
 /// @notice The L1 ERC721 bridge is a contract which works together with the L2 ERC721 bridge to
@@ -25,7 +26,15 @@ contract L1ERC721Bridge is ERC721Bridge, ISemver {
     /// @notice Constructs the L1ERC721Bridge contract.
     /// @param _messenger   Address of the CrossDomainMessenger on this network.
     /// @param _otherBridge Address of the ERC721 bridge on the other network.
-    constructor(address _messenger, address _otherBridge) ERC721Bridge(_messenger, _otherBridge) { }
+    constructor(address _messenger, address _otherBridge) ERC721Bridge(_messenger, _otherBridge) {
+        initialize(SuperchainConfig(address(0)));
+    }
+
+    /// @notice Initializes the contract.
+    /// @param _superchainConfig Address of the SuperchainConfig contract on this network.
+    function initialize(SuperchainConfig _superchainConfig) public initializer {
+        superChainConfig = _superchainConfig;
+    }
 
     /// @notice Completes an ERC721 bridge from the other domain and sends the ERC721 token to the
     ///         recipient on this domain.

packages/contracts-bedrock/src/universal/ERC721Bridge.sol

@@ -2,12 +2,16 @@
 pragma solidity 0.8.15;
 
 import { CrossDomainMessenger } from "src/universal/CrossDomainMessenger.sol";
+import { SuperchainConfig } from "src/L1/SuperchainConfig.sol";
 import { Address } from "@openzeppelin/contracts/utils/Address.sol";
 import { Initializable } from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
 
 /// @title ERC721Bridge
 /// @notice ERC721Bridge is a base contract for the L1 and L2 ERC721 bridges.
-abstract contract ERC721Bridge {
+abstract contract ERC721Bridge is Initializable {
+    /// @notice
+    SuperchainConfig public superChainConfig;
+
     /// @notice Messenger contract on this domain. This will be removed in the
     ///         future, use `messenger` instead.
     /// @custom:legacy
@@ -19,7 +23,7 @@ abstract contract ERC721Bridge {
     address public immutable OTHER_BRIDGE;
 
     /// @notice Reserve extra slots (to a total of 50) in the storage layout for future upgrades.
-    uint256[49] private __gap;
+    uint256[48] private __gap;
 
     /// @notice Emitted when an ERC721 bridge to the other network is initiated.
     /// @param localToken  Address of the token on this domain.