Log Autofill.Quality.*.ByFieldType by predicted type for unknown data.

Log Autofill.Quality.*.ByFieldType by predicted type for unknown data.

When the actual data type of an field cannot be determined (because it
was left empty or was populated with unknown data) log the ByFieldType
version of the metrics by the type predicted by autofill. This will
allow analysis of the false-positive rate broken down by type.

The previous version of the code was logging all of these under
Empty/Unknown => AMBIGUOUS.

The CL also fleshes out the ByFieldType enumeration in histograms.xml

BUG=710474
R=sebsg

Review-Url: https://codereview.chromium.org/2870163003
Cr-Original-Commit-Position: refs/heads/master@{#476766}
Review-Url: https://codereview.chromium.org/2923123005 .
Cr-Commit-Position: refs/branch-heads/3112@{#198}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed: https://chromium.googlesource.com/chromium/src/+/a7bf9ee09dc8641a1385ac2c48edfbd6400555f8

[Roger McFarlane (Chromium), 2017-06-06 19:15:56]

Description was changed from

==========
Log Autofill.Quality.*.ByFieldType by predicted type for unknown data.

When the actual data type of an field cannot be determined (because it
was left empty or was populated with unknown data) log the ByFieldType
version of the metrics by the type predicted by autofill. This will
allow analysis of the false-positive rate broken down by type.

The previous version of the code was logging all of these under
Empty/Unknown => AMBIGUOUS.

The CL also fleshes out the ByFieldType enumeration in histograms.xml

BUG=710474
R=sebsg

Review-Url: https://codereview.chromium.org/2870163003
Cr-Commit-Position: refs/heads/master@{#476766}
(cherry picked from commit 3c6caa287dacd94ee5e64eedaf44ea987f287bf8)
==========

to

==========
Log Autofill.Quality.*.ByFieldType by predicted type for unknown data.

When the actual data type of an field cannot be determined (because it
was left empty or was populated with unknown data) log the ByFieldType
version of the metrics by the type predicted by autofill. This will
allow analysis of the false-positive rate broken down by type.

The previous version of the code was logging all of these under
Empty/Unknown => AMBIGUOUS.

The CL also fleshes out the ByFieldType enumeration in histograms.xml

BUG=710474
R=sebsg

Review-Url: https://codereview.chromium.org/2870163003
Cr-Original-Commit-Position: refs/heads/master@{#476766}
Review-Url: https://codereview.chromium.org/2923123005 .
Cr-Commit-Position: refs/branch-heads/3112@{#198}
Cr-Branched-From:
b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed:
https://chromium.googlesource.com/chromium/src/+/a7bf9ee09dc8641a1385ac2c48ed...
==========

[Roger McFarlane (Chromium), 2017-06-06 19:15:57]

Committed patchset #1 (id:1) manually as
a7bf9ee09dc8641a1385ac2c48edfbd6400555f8.