[Global Media Controls] Add UMA to HardwareKeyMediaController

This CL records key presses in HardwareKeyMediaController for each
supported MediaSessionAction.

Bug: 921281
Change-Id: I0e2cbecc3a25fa2b850ff51830ecd9fc71023dce
Reviewed-on: https://chromium-review.googlesource.com/c/1435905
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#627732}(cherry picked from commit f36cc732d6568d9182516504715df9148a137573)
Reviewed-on: https://chromium-review.googlesource.com/c/1452461
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/branch-heads/3683@{#170}
Cr-Branched-From: e51029943e0a38dd794b73caaf6373d5496ae783-refs/heads/master@{#625896}
4 files changed