Improve apps v2 upgrade UX

remoting/webapp/crd/js/remoting.js

Index: remoting/webapp/crd/js/remoting.js
diff --git a/remoting/webapp/crd/js/remoting.js b/remoting/webapp/crd/js/remoting.js
index f80d9f064944d4708090450e080084fbdf45b037..b8acbd6bf7eb7260c65f16a244e0a27c4bb23bd8 100644
--- a/remoting/webapp/crd/js/remoting.js
+++ b/remoting/webapp/crd/js/remoting.js
@@ -21,8 +21,6 @@ remoting.initGlobalObjects = function() {
   if (base.isAppsV2()) {
     var htmlNode = /** @type {HTMLElement} */ (document.body.parentNode);
     htmlNode.classList.add('apps-v2');
-  } else {
-    migrateLocalToChromeStorage_();
   }
 
   console.log(remoting.getExtensionInfo());
@@ -89,10 +87,16 @@ remoting.getExtensionInfo = function() {
   }
 };
 
+remoting.onBeforeUnload = function() {
+  migrateLocalToChromeStorage_();
+  return remoting.promptClose();
+};
+
 /**
  * If an IT2Me client or host is active then prompt the user before closing.
  * If a Me2Me client is active then don't bother, since closing the window is
  * the more intuitive way to end a Me2Me session, and re-connecting is easy.
+ * @return {?string}
  */
 remoting.promptClose = function() {
   if (remoting.clientSession &&
@@ -242,15 +246,13 @@ function migrateLocalToChromeStorage_() {
       'oauth2-refresh-token',
       'oauth2-refresh-token-revokable',
       'oauth2-access-token',
-      'oauth2-xsrf-token',
-      'remoting-email'
+      'oauth2-xsrf-token'
   ];
   for (var setting in window.localStorage) {
     if (oauthSettings.indexOf(setting) == -1) {
-      var copy = {}
+      var copy = {};
       copy[setting] = window.localStorage.getItem(setting);
       chrome.storage.local.set(copy);
-      window.localStorage.removeItem(setting);
     }
   }
 }