Add new EXTRA_WEB_SEARCH_ONLY to RecognizerIntent API. This can be used to

avoid triggering any non-web-search actions from the speech recognizer
(such as Voice Actions in the Google implementation). The browser will set
this to true to avoid triggering non-web-search actions when speech
recognition is requested from the browser.

Change-Id: I9b410ef8696e12f22dbad325b367f0f187a2dce8
http://b/3289997
http://b/3176717