Add state batch deleted event (#145)

packages/contracts/contracts/optimistic-ethereum/OVM/chain/OVM_StateCommitmentChain.sol

@@ -450,6 +450,11 @@ contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, iRingBufferOverw
                 0
             )
         );
+
+        emit StateBatchDeleted(
+            _batchHeader.batchIndex,
+            _batchHeader.batchRoot
+        );
     }
 
     /**

packages/contracts/contracts/optimistic-ethereum/iOVM/chain/iOVM_StateCommitmentChain.sol

@@ -22,6 +22,11 @@ interface iOVM_StateCommitmentChain {
         bytes _extraData
     );
 
+    event StateBatchDeleted(
+        uint256 indexed _batchIndex,
+        bytes32 _batchRoot
+    );
+
     /********************
      * Public Functions *
      ********************/