Basic infrasture for RPC list added.

app/scripts/lib/controllers/preferences.js

@@ -4,7 +4,7 @@ const normalizeAddress = require('../sig-util').normalize
 class PreferencesController {
 
   constructor (opts = {}) {
-    const initState = opts.initState || {}
+    const initState = opts.initState || { frequentRPCList: [] }
     this.store = new ObservableStore(initState)
   }
 
@@ -12,7 +12,7 @@ class PreferencesController {
   // PUBLIC METHODS
   //
 
-  setSelectedAddress(_address) {
+  setSelectedAddress (_address) {
     return new Promise((resolve, reject) => {
       const address = normalizeAddress(_address)
       this.store.updateState({ selectedAddress: address })
@@ -20,10 +20,30 @@ class PreferencesController {
     })
   }
 
-  getSelectedAddress(_address) {
+  getSelectedAddress (_address) {
     return this.store.getState().selectedAddress
   }
 
+  addToFrequentRPCList (_url) {
+    return new Promise((resolve, reject) => {
+      let rpcList = this.getFrequentRPCList()
+      let index = rpcList.findIndex((element) => { element === _url })
+      if (index) {
+        rpcList.splice(index, 1)
+      }
+      if (rpcList.length >= 3) {
+        rpcList.shift()
+      }
+      rpcList.push(_url)
+      this.store.updateState({ frequentRPCList: rpcList })
+      resolve()
+    })
+  }
+
+  getFrequentRPCList () {
+    return this.store.getState().frequentRPCList
+  }
+
   //
   // PRIVATE METHODS
   //

app/scripts/metamask-controller.js

@@ -259,6 +259,7 @@ module.exports = class MetamaskController extends EventEmitter {
 
       // PreferencesController
       setSelectedAddress:        nodeify(preferencesController.setSelectedAddress).bind(preferencesController),
+      setFrequentRPCList:        nodeify(preferencesController.setFrequentRPCList).bind(preferencesController),
 
       // KeyringController
       setLocked:                 nodeify(keyringController.setLocked).bind(keyringController),