Record UMA histogram when Form-Not-Secure warning is shown

Record UMA histogram when Form-Not-Secure warning is shown

This records a histogram, at most once per main-frame navigation, when "Login
not secure" is shown in a password form. This will allow us to measure the
frequency of the warning (e.g. the number of times the warning is shown per
million navigations.)

BUG=687823
Review-Url: https://codereview.chromium.org/2670733002
Cr-Commit-Position: refs/heads/master@{#447960}
(cherry picked from commit ce9ab459b6cce4f6d327b83ef49a8684a8839b9b)

Review-Url: https://codereview.chromium.org/2678113002 .
Cr-Commit-Position: refs/branch-heads/2987@{#340}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/15c16d7dd4f47fe47b20e4626fc05084cf533218

[estark, 2017-02-06 19:15:55]

Description was changed from

==========
Record UMA histogram when Form-Not-Secure warning is shown

This records a histogram, at most once per main-frame navigation, when "Login
not secure" is shown in a password form. This will allow us to measure the
frequency of the warning (e.g. the number of times the warning is shown per
million navigations.)

BUG=687823

Review-Url: https://codereview.chromium.org/2670733002
Cr-Commit-Position: refs/heads/master@{#447960}
(cherry picked from commit ce9ab459b6cce4f6d327b83ef49a8684a8839b9b)
==========

to

==========
Record UMA histogram when Form-Not-Secure warning is shown

This records a histogram, at most once per main-frame navigation, when "Login
not secure" is shown in a password form. This will allow us to measure the
frequency of the warning (e.g. the number of times the warning is shown per
million navigations.)

BUG=687823

Review-Url: https://codereview.chromium.org/2670733002
Cr-Commit-Position: refs/heads/master@{#447960}
(cherry picked from commit ce9ab459b6cce4f6d327b83ef49a8684a8839b9b)

Review-Url: https://codereview.chromium.org/2678113002 .
Cr-Commit-Position: refs/branch-heads/2987@{#340}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/15c16d7dd4f47fe47b20e4626fc0...
==========

[estark, 2017-02-06 19:15:57]

Committed patchset #1 (id:1) manually as
15c16d7dd4f47fe47b20e4626fc05084cf533218.