There are way to sync cookie in webview

in Webview Activity

when : onCreate
->  CookieSyncManager.createInstance(this);

when : onResum
-> CookieSyncManager.getInstance().startSync();

when : onPasue
-> CookieSyncManager.getInstance().stopSync();

When : onDestory 

-> CookieManager.getInstance().removeSessionCookie();

in WebClient

when : onPageFinished

-> CookieSyncManager.getInstance().sync();

that is all when you make a webapp application with session