Set site engagement timestamps to privacy-respectful values when history is cleared.

Set site engagement timestamps to privacy-respectful values when history is cleared.

The site engagement service stores last updated and last shortcut launch
timestamps per origin. When history is cleared, the former is set to the
time of history clearing and the latter is not changed.

This CL sets both timestamps to the time of the most recent remaining
visit in history for that origin once history clearing is completed. The
last shortcut launch time is only set if it was non-null prior to the
history being cleared.

A slight change to the history service query (adding the last visited date
to the data returned) is necessary to enable this change. More
comprehensive testing of the history expiry mechanism are added to
ensure correctness.

BUG=604284
Review URL: https://codereview.chromium.org/1901563002

Cr-Commit-Position: refs/heads/master@{#388321}
(cherry picked from commit 3d900e9e2c2dc6cda11c94aea9848181a9b4ffd1)

Committed: https://chromium.googlesource.com/chromium/src/+/860a9e7ace12d0376f6698560c7a4a17c4f8cf04

[dominickn, 2016-04-21 06:09:38]

Description was changed from

==========
Set site engagement timestamps to privacy-respectful values when history is
cleared.

The site engagement service stores last updated and last shortcut launch
timestamps per origin. When history is cleared, the former is set to the
time of history clearing and the latter is not changed.

This CL sets both timestamps to the time of the most recent remaining
visit in history for that origin once history clearing is completed. The
last shortcut launch time is only set if it was non-null prior to the
history being cleared.

A slight change to the history service query (adding the last visited date
to the data returned) is necessary to enable this change. More
comprehensive testing of the history expiry mechanism are added to
ensure correctness.

BUG=604284

Review URL: https://codereview.chromium.org/1901563002

Cr-Commit-Position: refs/heads/master@{#388321}
(cherry picked from commit 3d900e9e2c2dc6cda11c94aea9848181a9b4ffd1)
==========

to

==========
Set site engagement timestamps to privacy-respectful values when history is
cleared.

The site engagement service stores last updated and last shortcut launch
timestamps per origin. When history is cleared, the former is set to the
time of history clearing and the latter is not changed.

This CL sets both timestamps to the time of the most recent remaining
visit in history for that origin once history clearing is completed. The
last shortcut launch time is only set if it was non-null prior to the
history being cleared.

A slight change to the history service query (adding the last visited date
to the data returned) is necessary to enable this change. More
comprehensive testing of the history expiry mechanism are added to
ensure correctness.

BUG=604284

Review URL: https://codereview.chromium.org/1901563002

Cr-Commit-Position: refs/heads/master@{#388321}
(cherry picked from commit 3d900e9e2c2dc6cda11c94aea9848181a9b4ffd1)

Committed:
https://chromium.googlesource.com/chromium/src/+/860a9e7ace12d0376f6698560c7a...
==========

[dominickn, 2016-04-21 06:09:42]

Committed patchset #1 (id:1) manually as
860a9e7ace12d0376f6698560c7a4a17c4f8cf04.