bluetooth: Test for when adapter is not present/off.

bluetooth: Test for when adapter is not present/off.

Three-way patch to add a message for when Bluetooth Adapter is off:
 [1] Add constant to public WebBluetoothError. (http://crrev.com/1267843005)
 [2] Add check for off adapter and add fake adapters. (http://crrev.com/1264323002)
 [3] This patch.

BUG=515573
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200209

[ortuno, 2015-08-03 23:02:18]

ortuno@chromium.org changed reviewers:
+ jyasskin@chromium.org

[ortuno, 2015-08-03 23:02:18]

@jyasskin: PTAL

[Jeffrey Yasskin, 2015-08-05 20:53:31]

lgtm

[ortuno, 2015-08-05 20:59:15]

ortuno@chromium.org changed reviewers:
+ scheib@chromium.org

[ortuno, 2015-08-05 20:59:16]

@scheib: PTAL

[scheib, 2015-08-05 21:36:31]

LGTM (with upstream patch fixed)

[ortuno, 2015-08-08 00:02:14]

The CQ bit was checked by ortuno@chromium.org

[commit-bot: I haz the power, 2015-08-08 00:02:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1261993012/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1261993012/20001

[commit-bot: I haz the power, 2015-08-08 02:30:24]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200209