[Password Generation] Fix breakage that prevents filling of generated passwords

[Password Generation] Fix breakage that prevents filling of generated passwords

This bug was introduced in the move from RenderViewHost -> RenderFrameHost.
The Interactive UI test would have caught this, but was disabled for being
flaky. I'm actively working on fixing that test, but given the severity of the
problem it makes sense to check in the fix without waiting for the test to
be fixed.

BUG=440257
Committed: https://crrev.com/2baf737555fb43ee6296be5d2e2562b6f3562a24
Cr-Commit-Position: refs/heads/master@{#308173}

[Garrett Casto, 2014-12-12 08:53:27]

Patchset #1 (id:1) has been deleted

[Garrett Casto, 2014-12-12 08:54:49]

gcasto@chromium.org changed reviewers:
+ estade@chromium.org, vabr@chromium.org

[Garrett Casto, 2014-12-12 08:54:50]

Evan - Autofill changes.
Vaclav - Password changes.

[vabr (Chromium), 2014-12-12 09:17:22]

LGTM.
So the problem was for cases when the driver did not correspond to the main
frame?

Cheers,
Vaclav

[Evan Stade, 2014-12-12 19:47:12]

lgtm, sorry for breakage and thanks for fix.

[Garrett Casto, 2014-12-12 20:45:45]

Vaclav - It actually failed on all frames as far as I could tell. 

Evan - Don't worry about it. My fault for the test being broken.

[Garrett Casto, 2014-12-12 20:45:50]

The CQ bit was checked by gcasto@chromium.org

[Garrett Casto, 2014-12-12 20:46:19]

The CQ bit was checked by gcasto@chromium.org

[commit-bot: I haz the power, 2014-12-12 20:47:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/790783003/20001

[commit-bot: I haz the power, 2014-12-12 21:59:30]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2014-12-12 22:01:07]

Patchset 1 (id:??) landed as
https://crrev.com/2baf737555fb43ee6296be5d2e2562b6f3562a24
Cr-Commit-Position: refs/heads/master@{#308173}