cros: Add metric ApplistAppLaunchedV2

This new metric, AppListAppLaunchedV2, tracks the state of the app
list during an app launch from the app list and shelf. This metric
has 8 different suffixes, one for each unique app list state. The
metric also has 4 buckets, which represent the source of the app
launch (Grid, SuggestionChip, SearchBox, Shelf).

This new metric also takes into account apps launched through context
menus. In the case of context menus, the bucket used for the app
launch is wherever the context menu was opened from.

Bug: 837290
Change-Id: Ie945ec6379dc1c1e48a300f01a7517f98761d377
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1526594
Reviewed-by: Emily Stark <estark@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Commit-Queue: Matthew Mourgos <mmourgos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652166}
24 files changed