@0x/contracts-storage: Move init() out of IStaking and into IStorageInit.

contracts/staking/contracts/src/StakingProxy.sol

@@ -22,7 +22,7 @@ import "@0x/contracts-utils/contracts/src/Ownable.sol";
 import "./libs/LibProxy.sol";
 import "./immutable/MixinStorage.sol";
 import "./immutable/MixinHyperParameters.sol";
-import "./interfaces/IStaking.sol";
+import "./interfaces/IStorageInit.sol";
 import "./interfaces/IStakingProxy.sol";
 
 contract StakingProxy is
@@ -72,7 +72,7 @@ contract StakingProxy is
         readOnlyProxyCallee = _stakingContract;
         // Call `init()` on the staking contract to initialize storage.
         (bool didInitSucceed, bytes memory initReturnData) =
-            _stakingContract.delegatecall(abi.encode(IStaking(0).init.selector));
+            stakingContract.delegatecall(abi.encode(IStorageInit(0).init.selector));
         if (!didInitSucceed) {
             assembly { revert(add(initReturnData, 0x20), mload(initReturnData)) }
         }

contracts/staking/contracts/src/interfaces/IStaking.sol

@@ -20,11 +20,6 @@ pragma solidity ^0.5.9;
 
 
 interface IStaking {
-    /// @dev Initialize storage owned by this contract.
-    ///      This function should not be called directly.
-    ///      The StakingProxy contract will call it in `attachStakingContract()`.
-    function init() external;
-
     /// @dev Pays a protocol fee in ETH.
     /// @param makerAddress The address of the order's maker.
     /// @param payerAddress The address that is responsible for paying the protocol fee.

contracts/staking/contracts/src/interfaces/IStorageInit.sol

@@ -0,0 +1,25 @@
+/*
+
+  Copyright 2019 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.5.9;
+
+
+interface IStorageInit {
+    /// @dev Initialize storage owned by this contract.
+    function init() external;
+}