Enable audio permissions in manifest for WebAudio

Change-Id: Ib0c5caf34c71026cfde5b3c3ab1b4485a0ad7b06
browser: Privacy Guard support

 * Return empty lists for query of bookmarks and history when privacy
   guard is active for the calling process.

Change-Id: I6a20ad481ae60d1e062833db43d1c2fdfe43c687