Credential Manager: Expose the runtime flag to the embedder.

Credential Manager: Expose the runtime flag to the embedder.

The credential manager's current implementation exposes sensitive
information to websites via a JavaScript API. Until we have a good feel
for exactly what we want to expose, how we want to expose it, and what
UI needs to be tied to that exposure, we shouldn't enable this via the
general "Experimental Web Features" flag.

We do want to enable testing, though: creating a separate flag on
about:flags seems like a reasonable way of containing the risk.

BUG=400674
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=183065

[Mike West, 2014-10-01 12:33:50]

mkwst@chromium.org changed reviewers:
+ jochen@chromium.org

[Mike West, 2014-10-01 12:33:51]

WDYT, friendly public/ OWNER?

-mike

[jochen (gone - plz use gerrit), 2014-10-01 14:04:13]

lgtm

[Mike West, 2014-10-01 14:05:18]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2014-10-01 14:06:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/617003006/1

[commit-bot: I haz the power, 2014-10-01 15:28:04]

Committed patchset #1 (id:1) as 183065