Cleanup the JavaScript code of session

lib/browser/api/session.js

@@ -1,14 +1,12 @@
+const {EventEmitter} = require('events')
 const bindings = process.atomBinding('session')
+
 const PERSIST_PREFIX = 'persist:'
 
 // Returns the Session from |partition| string.
-exports.fromPartition = function (partition) {
-  if (partition == null) {
-    partition = ''
-  }
-  if (partition === '') {
-    return exports.defaultSession
-  }
+exports.fromPartition = function (partition = '') {
+  if (partition === '') return exports.defaultSession
+
   if (partition.startsWith(PERSIST_PREFIX)) {
     return bindings.fromPartition(partition.substr(PERSIST_PREFIX.length), false)
   } else {
@@ -23,3 +21,10 @@ Object.defineProperty(exports, 'defaultSession', {
     return bindings.fromPartition('', false)
   }
 })
+
+const wrapSession = function (session) {
+  // Session is an EventEmitter.
+  Object.setPrototypeOf(session, EventEmitter.prototype)
+}
+
+bindings._setWrapSession(wrapSession)

lib/browser/api/web-contents.js

@@ -5,7 +5,6 @@ const {ipcMain, Menu, NavigationController} = require('electron')
 
 const binding = process.atomBinding('web_contents')
 const debuggerBinding = process.atomBinding('debugger')
-const sessionBinding = process.atomBinding('session')
 
 let nextId = 0
 
@@ -212,14 +211,8 @@ let wrapDebugger = function (webContentsDebugger) {
   Object.setPrototypeOf(webContentsDebugger, EventEmitter.prototype)
 }
 
-var wrapSession = function (session) {
-  // session is an EventEmitter.
-  Object.setPrototypeOf(session, EventEmitter.prototype)
-}
-
 binding._setWrapWebContents(wrapWebContents)
 debuggerBinding._setWrapDebugger(wrapDebugger)
-sessionBinding._setWrapSession(wrapSession)
 
 module.exports = {
   create (options = {}) {