feat(protocol): Add TaikoGovernor (#15228)

Co-authored-by: Daniel Wang <dong77@gmail.com>

packages/protocol/contracts/L1/TaikoToken.sol

@@ -44,9 +44,9 @@ contract TaikoToken is
         initializer
     {
         EssentialContract._init(_addressManager);
-        ERC20Upgradeable.__ERC20_init_unchained(_name, _symbol);
-        ERC20SnapshotUpgradeable.__ERC20Snapshot_init_unchained();
-        ERC20VotesUpgradeable.__ERC20Votes_init_unchained();
+        ERC20Upgradeable.__ERC20_init(_name, _symbol);
+        ERC20SnapshotUpgradeable.__ERC20Snapshot_init();
+        ERC20VotesUpgradeable.__ERC20Votes_init();
 
         // Mint 1 billion tokens
         _mint(_recipient, 1_000_000_000 ether);

packages/protocol/contracts/L1/gov/TaikoGovernor.sol

@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.2;
+
+import "lib/openzeppelin-contracts/contracts/governance/Governor.sol";
+import
+    "lib/openzeppelin-contracts/contracts/governance/compatibility/GovernorCompatibilityBravo.sol";
+import
+    "lib/openzeppelin-contracts/contracts/governance/extensions/GovernorVotes.sol";
+import
+    "lib/openzeppelin-contracts/contracts/governance/extensions/GovernorVotesQuorumFraction.sol";
+import
+    "lib/openzeppelin-contracts/contracts/governance/extensions/GovernorTimelockControl.sol";
+
+contract TaikoGovernor is
+    Governor,
+    GovernorCompatibilityBravo,
+    GovernorVotes,
+    GovernorVotesQuorumFraction,
+    GovernorTimelockControl
+{
+    constructor(
+        IVotes _token,
+        TimelockController _timelock
+    )
+        Governor("MyGovernor")
+        GovernorVotes(_token)
+        GovernorVotesQuorumFraction(4)
+        GovernorTimelockControl(_timelock)
+    { }
+
+    // How long after a proposal is created should voting power be fixed. A
+    // large voting delay gives users time to unstake tokens if necessary.
+    function votingDelay() public pure override returns (uint256) {
+        return 7200; // 1 day
+    }
+
+    // How long does a proposal remain open to votes.
+    function votingPeriod() public pure override returns (uint256) {
+        return 50_400; // 1 week
+    }
+
+    // The number of votes required in order for a voter to become a proposer
+    function proposalThreshold() public pure override returns (uint256) {
+        return 1_000_000_000 ether / 10_000; // 0.01% of Taiko Token
+    }
+
+    // The functions below are overrides required by Solidity.
+    function state(uint256 proposalId)
+        public
+        view
+        override(Governor, IGovernor, GovernorTimelockControl)
+        returns (ProposalState)
+    {
+        return super.state(proposalId);
+    }
+
+    function propose(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        string memory description
+    )
+        public
+        override(Governor, IGovernor, GovernorCompatibilityBravo)
+        returns (uint256)
+    {
+        return super.propose(targets, values, calldatas, description);
+    }
+
+    function _execute(
+        uint256 proposalId,
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    )
+        internal
+        override(Governor, GovernorTimelockControl)
+    {
+        super._execute(proposalId, targets, values, calldatas, descriptionHash);
+    }
+
+    function _cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 descriptionHash
+    )
+        internal
+        override(Governor, GovernorTimelockControl)
+        returns (uint256)
+    {
+        return super._cancel(targets, values, calldatas, descriptionHash);
+    }
+
+    function _executor()
+        internal
+        view
+        override(Governor, GovernorTimelockControl)
+        returns (address)
+    {
+        return super._executor();
+    }
+
+    function supportsInterface(bytes4 interfaceId)
+        public
+        view
+        override(Governor, IERC165, GovernorTimelockControl)
+        returns (bool)
+    {
+        return super.supportsInterface(interfaceId);
+    }
+}