Set cookie for both gwt and polygerrit UI

Change-Id: I33927d817ca46cce053a44d5759476faca1815ac

background.js

diff --git a/background.js b/background.js
index 0f8cfdf..6744618 100644
--- a/background.js
+++ b/background.js
@@ -204,9 +204,17 @@
     url: tab.url,
   };
   chrome.cookies.get(cookieID, function(cookie) {
-    if (cookie) {
+    if (cookie && cookie.value === 'polygerrit') {
       ga('send', 'event', 'Page Action', 'Switch to Gerrit');
-      chrome.cookies.remove(cookieID, function() {
+      chrome.cookies.set({
+        expirationDate: twoYearsFromNow,
+        url: tab.url,
+        name: 'GERRIT_UI',
+        value: 'gwt',
+        httpOnly: true,
+        path: '/',
+        secure: true,
+      }, function() {
         // The GWT UI does not handle PolyGerrit URL redirection.
         chrome.tabs.update(tab.id, {
           url: getGWTRedirectURL(new URL(tab.url)),

manifest.json

diff --git a/manifest.json b/manifest.json
index 2a6aa49..772df9a 100644
--- a/manifest.json
+++ b/manifest.json
@@ -2,7 +2,7 @@
   "manifest_version": 2,
   "name": "Gerrit UI Switcher",
   "description": "Easily switch between the current Gerrit UI and the new PolyGerrit UI",
-  "version": "0.5.4",
+  "version": "0.6.0",
   "background": {
     "scripts": [
       "background.js"