Merge 285314 "Turn webspeech on/off when tab goes fore/background"

Merge 285314 "Turn webspeech on/off when tab goes fore/background"

> Turn webspeech on/off when tab goes fore/background
> 
> This change adds a toggle to turn webspeech off when tab goes background.
> And further request to turn media capture devices on will be denied.
> So Both WebRTC and webSpeech won't be able to initiate new requests when tab is in background.
> 
> This CL also fixed a bug in the original CL that was reverted: some times recognition will not be aborted immediately after screen lock.
> The issue is caused by that calling abort() will not delete the session in SpeechRecognitionManagerImpl.
> So if a SpeechRecognition objects calls multiple start(), several sessions with the same request_id will be created.
> And when passing the request_id to abort the sessions, only 1 session will be aborted
> This change requests the all sessions in the same render view to be aborted.
> Thus solving the above issue.
> 
> BUG=396054
> R=jochen@chromium.org, tsepez@chromium.org, xians@chromium.org
> 
> Review URL: https://codereview.chromium.org/415933002

TBR=qinmin@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285317

[qinmin, 2014-07-24 17:47:46]

Committed patchset #1 manually as r285317.