diff --git a/atom/browser/api/atom_api_session.cc b/atom/browser/api/atom_api_session.cc
index 7ce902484eab..eecb2521b77a 100644
--- a/atom/browser/api/atom_api_session.cc
+++ b/atom/browser/api/atom_api_session.cc
@@ -164,6 +164,8 @@ namespace api {
 
 namespace {
 
+const char kPersistPrefix[] = "persist:";
+
 // The wrapSession funtion which is implemented in JavaScript
 using WrapSessionCallback = base::Callback<void(v8::Local<v8::Value>)>;
 WrapSessionCallback g_wrap_session;
@@ -534,10 +536,19 @@ mate::Handle<Session> Session::CreateFrom(
 
 // static
 mate::Handle<Session> Session::FromPartition(
-    v8::Isolate* isolate, const std::string& partition, bool in_memory) {
-  auto browser_context = brightray::BrowserContext::From(partition, in_memory);
-  return CreateFrom(isolate,
-                    static_cast<AtomBrowserContext*>(browser_context.get()));
+    v8::Isolate* isolate, const std::string& partition) {
+  scoped_refptr<brightray::BrowserContext> browser_context;
+  if (partition.empty()) {
+    browser_context = brightray::BrowserContext::From("", false);
+  } else if (base::StartsWith(partition, kPersistPrefix,
+                              base::CompareCase::SENSITIVE)) {
+    std::string name = partition.substr(8);
+    browser_context = brightray::BrowserContext::From(name, false);
+  } else {
+    browser_context = brightray::BrowserContext::From(partition, true);
+  }
+  return CreateFrom(
+      isolate, static_cast<AtomBrowserContext*>(browser_context.get()));
 }
 
 // static
@@ -578,13 +589,12 @@ void SetWrapSession(const WrapSessionCallback& callback) {
 namespace {
 
 v8::Local<v8::Value> FromPartition(
-    const std::string& partition, bool in_memory, mate::Arguments* args) {
+    const std::string& partition, mate::Arguments* args) {
   if (!atom::Browser::Get()->is_ready()) {
     args->ThrowError("Session can only be received when app is ready");
     return v8::Null(args->isolate());
   }
-  return atom::api::Session::FromPartition(
-      args->isolate(), partition, in_memory).ToV8();
+  return atom::api::Session::FromPartition(args->isolate(), partition).ToV8();
 }
 
 void Initialize(v8::Local<v8::Object> exports, v8::Local<v8::Value> unused,
diff --git a/atom/browser/api/atom_api_session.h b/atom/browser/api/atom_api_session.h
index 0868cbe18bee..d1943ba6ed1e 100644
--- a/atom/browser/api/atom_api_session.h
+++ b/atom/browser/api/atom_api_session.h
@@ -47,9 +47,9 @@ class Session: public mate::TrackableObject<Session>,
   static mate::Handle<Session> CreateFrom(
       v8::Isolate* isolate, AtomBrowserContext* browser_context);
 
-  // Gets the Session of |partition| and |in_memory|.
+  // Gets the Session of |partition|.
   static mate::Handle<Session> FromPartition(
-      v8::Isolate* isolate, const std::string& partition, bool in_memory);
+      v8::Isolate* isolate, const std::string& partition);
 
   AtomBrowserContext* browser_context() const { return browser_context_.get(); }
 
diff --git a/atom/browser/api/atom_api_web_contents.cc b/atom/browser/api/atom_api_web_contents.cc
index 8622942668b0..48ef3ce03e00 100644
--- a/atom/browser/api/atom_api_web_contents.cc
+++ b/atom/browser/api/atom_api_web_contents.cc
@@ -285,16 +285,11 @@ WebContents::WebContents(v8::Isolate* isolate,
   std::string partition;
   mate::Handle<api::Session> session;
   if (options.Get("session", &session)) {
-  } else if (options.Get("partition", &partition) && !partition.empty()) {
-    bool in_memory = true;
-    if (base::StartsWith(partition, "persist:", base::CompareCase::SENSITIVE)) {
-      in_memory = false;
-      partition = partition.substr(8);
-    }
-    session = Session::FromPartition(isolate, partition, in_memory);
+  } else if (options.Get("partition", &partition)) {
+    session = Session::FromPartition(isolate, partition);
   } else {
     // Use the default session if not specified.
-    session = Session::FromPartition(isolate, "", false);
+    session = Session::FromPartition(isolate, "");
   }
   session_.Reset(isolate, session.ToV8());
 
diff --git a/lib/browser/api/session.js b/lib/browser/api/session.js
index 2fa0baca98da..86a7902ef597 100644
--- a/lib/browser/api/session.js
+++ b/lib/browser/api/session.js
@@ -2,24 +2,15 @@ const {EventEmitter} = require('events')
 const {app} = require('electron')
 const {fromPartition, _setWrapSession} = process.atomBinding('session')
 
-const PERSIST_PREFIX = 'persist:'
-
-// Returns the Session from |partition| string.
-exports.fromPartition = function (partition = '') {
-  if (partition === '') return exports.defaultSession
-
-  if (partition.startsWith(PERSIST_PREFIX)) {
-    return fromPartition(partition.substr(PERSIST_PREFIX.length), false)
-  } else {
-    return fromPartition(partition, true)
-  }
-}
-
 // Returns the default session.
-Object.defineProperty(exports, 'defaultSession', {
-  enumerable: true,
-  get: function () {
-    return fromPartition('', false)
+Object.defineProperties(exports, {
+  defaultSession: {
+    enumerable: true,
+    get () { return fromPartition('') }
+  },
+  fromPartition: {
+    enumerable: true,
+    value: fromPartition
   }
 })