Revert "Don't record first filling result for sign-in forms"

This reverts commit 34d69265b1f1f5a3c7739827a0b7e05bfc928e08.

Reason for revert: breaks msan
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20MSan%20Tests/14500

Original change's description:
> Don't record first filling result for sign-in forms
> 
> The new form parser may decide that a form has no current-password element, but
> only new-password / confirmation elements. In this case, the parser sets the
> unique_renderer_id to 'undefined'. The credentials will be sent to the renderer
> for filling via manual fallback but the renderer won't ever fill (as there is
> no password element defined for filling.
> 
> This CL ensures that this case does not get recorded as a failure to fill. This
> is important because we record two metrics about the first fill attempt:
> PasswordManager.FirstWaitForUsernameReason and
> PasswordManager.FirstRendererFillingResult For websites that have a sign-up
> form followed by a sign-in form, we don't want to record the failure to fill on
> the sign-up form.
> 
> Bug: 918846
> Change-Id: I79e9a73ae3573a81e121eaa483e0ecef0889184f
> Reviewed-on: https://chromium-review.googlesource.com/c/1422018
> Commit-Queue: Dominic Battré <battre@chromium.org>
> Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#625178}

TBR=battre@chromium.org,dvadym@chromium.org

Change-Id: I3c68004b67b5fcc65511c611c2d205297596e782
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 918846
Reviewed-on: https://chromium-review.googlesource.com/c/1430581
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625227}
4 files changed