Metrics for feature engagement tracker.

Metrics for feature engagement tracker.

This CL adds metrics for feature engagement tracker.

There are some user actions which are not const char literal, this is
probably not ok, so we probably can't use suffixes for user actions.

Bug: 726155
Change-Id: Ieb0ca4cf5c49b9f2cd6d7eed5f6afe9fea4faa20
Reviewed-on: https://chromium-review.googlesource.com/514331
Commit-Queue: Xing Liu <xingliu@chromium.org>;
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>;
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>;
Reviewed-by: David Trainor <dtrainor@chromium.org>;
Cr-Original-Commit-Position: refs/heads/master@{#475691}
Review-Url: https://codereview.chromium.org/2911123003 .
Cr-Commit-Position: refs/branch-heads/3112@{#43}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed: https://chromium.googlesource.com/chromium/src/+/b36844f6112ee001d289dda31a858122b23c3852

[xingliu, 2017-05-31 00:08:35]

Description was changed from

==========
Metrics for feature engagement tracker.

This CL adds metrics for feature engagement tracker.

There are some user actions which are not const char literal, this is
probably not ok, so we probably can't use suffixes for user actions.

Bug: 726155
Change-Id: Ieb0ca4cf5c49b9f2cd6d7eed5f6afe9fea4faa20
Reviewed-on: https://chromium-review.googlesource.com/514331
Commit-Queue: Xing Liu <xingliu@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#475691}
(cherry picked from commit 92cb438681b00aa996bdc0bac4187de2dac1ad68)
==========

to

==========
Metrics for feature engagement tracker.

This CL adds metrics for feature engagement tracker.

There are some user actions which are not const char literal, this is
probably not ok, so we probably can't use suffixes for user actions.

Bug: 726155
Change-Id: Ieb0ca4cf5c49b9f2cd6d7eed5f6afe9fea4faa20
Reviewed-on: https://chromium-review.googlesource.com/514331
Commit-Queue: Xing Liu <xingliu@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#475691}
Review-Url: https://codereview.chromium.org/2911123003 .
Cr-Commit-Position: refs/branch-heads/3112@{#43}
Cr-Branched-From:
b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed:
https://chromium.googlesource.com/chromium/src/+/b36844f6112ee001d289dda31a85...
==========

[xingliu, 2017-05-31 00:08:36]

Committed patchset #1 (id:1) manually as
b36844f6112ee001d289dda31a858122b23c3852.