[Android] Add UMA for pull-to-refresh activation

[Android] Add UMA for pull-to-refresh activation

Add a baseline metric for the number of page reloads triggered by the
new pull-to-refresh gesture, allowing comparison with other avenues
for page reload (e.g., from toolbar reload icon).

BUG=442505
Committed: https://crrev.com/07e2788ed69fa76cb427884ea8f05807fd6a1806
Cr-Commit-Position: refs/heads/master@{#308477}

[jdduke (slow), 2014-12-15 23:00:22]

jdduke@chromium.org changed reviewers:
+ tedchoc@chromium.org

[jdduke (slow), 2014-12-15 23:00:23]

tedcho@: I've never used the "UserMetricsAction" construct (have always used the
histogram macros directly), just following the pattern for toolbar-initiated
reloads here.

[Ted C, 2014-12-15 23:02:37]

lgtm

[jdduke (slow), 2014-12-15 23:56:32]

jdduke@chromium.org changed reviewers:
+ isherman@chromium.org

[jdduke (slow), 2014-12-15 23:56:33]

+isherman@ for tools/metrics/actions review.

[Ilya Sherman, 2014-12-16 00:34:01]

metrics lgtm

[jdduke (slow), 2014-12-16 00:38:04]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-12-16 00:39:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/803343002/1

[commit-bot: I haz the power, 2014-12-16 00:45:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-16 00:46:21]

Patchset 1 (id:??) landed as
https://crrev.com/07e2788ed69fa76cb427884ea8f05807fd6a1806
Cr-Commit-Position: refs/heads/master@{#308477}