Added function to get list of networks with prefetched passwords.

Added function to get list of networks with prefetched passwords.

Added function that allows javascript apps using gcdPrivate to get a list of networks with prefetched passwords.

Rebase of https://codereview.chromium.org/427123002

BUG=383167
TBR=asargent@chromium.org,noamsml@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287049

[Vitaly Buka (NO REVIEWS), 2014-07-31 21:09:50]

The CQ bit was checked by vitalybuka@chromium.org

[commit-bot: I haz the power, 2014-07-31 21:13:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vitalybuka@chromium.org/434733003/1

[Vitaly Buka (NO REVIEWS), 2014-07-31 21:37:46]

The CQ bit was checked by vitalybuka@chromium.org

[commit-bot: I haz the power, 2014-07-31 21:39:58]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vitalybuka@chromium.org/434733003/20001

[commit-bot: I haz the power, 2014-08-01 03:22:23]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_x64_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-01 18:24:15]

Change committed as 287049

[Noam Samuel, 2014-08-01 18:29:18]

lgtm

[erikchen, 2014-08-01 21:28:41]

A revert of this CL has been created in
https://codereview.chromium.org/433703003/ by erikchen@chromium.org.

The reason for reverting is: breaks win7 browser tests.
GcdPrivateAPITest.WifiPasswords

http://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%28....