Adds getPendingNonce method to provider initialization options in metamask-controller.

app/scripts/controllers/network/createMetamaskMiddleware.js

@@ -38,6 +38,6 @@ function createPendingNonceMiddleware ({ getPendingNonce }) {
     const address = req.params[0]
     const blockRef = req.params[1]
     if (blockRef !== 'pending') return next()
-    req.result = await getPendingNonce(address)
+    res.result = await getPendingNonce(address)
   })
 }

app/scripts/metamask-controller.js

@@ -268,6 +268,7 @@ module.exports = class MetamaskController extends EventEmitter {
       // msg signing
       processEthSignMessage: this.newUnsignedMessage.bind(this),
       processPersonalMessage: this.newUnsignedPersonalMessage.bind(this),
+      getPendingNonce: this.getPendingNonce.bind(this),
     }
     const providerProxy = this.networkController.initializeProvider(providerOpts)
     return providerProxy
@@ -1362,6 +1363,19 @@ module.exports = class MetamaskController extends EventEmitter {
     return '0x' + percentileNumBn.mul(GWEI_BN).toString(16)
   }
 
+  /**
+   * Returns the nonce that will be associated with a transaction once approved
+   * @param address {string} - The hex string address for the transaction
+   * @returns Promise<number>
+   */
+  async getPendingNonce (address) {
+    const { nonceDetails, releaseLock} = await this.txController.nonceTracker.getNonceLock(address)
+    const pendingNonce = nonceDetails.params.highestSuggested
+
+    releaseLock()
+    return pendingNonce
+  }
+
 //=============================================================================
 // CONFIG
 //=============================================================================