getting user identity from chrome store.
manifest.json ->
   key - copied from the manifest.json created in the application data directory. (this remains same and is attached to the api id).
   oauth2 -> authorisation scheme to get permission to access the user private data.
             client_id -> generated in google's developer console 'https://console.developers.google.com/project?authuser=0'.
             scope - the parameters here determine the various API access needed by the app.
             NOTE- the APIs like Google+ API should be enabled for this to work.
             individual scopes can be seen in developer console website.
   permissions: identity permission to enable the chrome.identity API and other sites permission (copied from the sample_chrome_apps 'Identity').

Created a dummy method to ask the user's consent (interactive = true) to get the desired information.