Merge M57: "Add metric for tracking media playback utilization."

Merge M57: "Add metric for tracking media playback utilization."

I.e., how many players completed preload but never saw playback. This
will be handy in terms of guiding efforts to reduce the number of these
types of "useless" players. I.e. maybe deferred offscreen loading, etc.

BUG=694855
TEST=manual

Review-Url: https://codereview.chromium.org/2709903002
Cr-Commit-Position: refs/heads/master@{#452135}
(cherry picked from commit 35848da5131b081ee4751be9669230223baf7c43)

Review-Url: https://codereview.chromium.org/2711803006 .
Cr-Commit-Position: refs/branch-heads/2987@{#667}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/24d1a80b879c17c908312ffdd84c8c6b76ad325a

[DaleCurtis, 2017-02-23 20:01:19]

Description was changed from

==========
Merge M57: "Add metric for tracking media playback utilization."

I.e., how many players completed preload but never saw playback. This
will be handy in terms of guiding efforts to reduce the number of these
types of "useless" players. I.e. maybe deferred offscreen loading, etc.

BUG=694855
TEST=manual

Review-Url: https://codereview.chromium.org/2709903002
Cr-Commit-Position: refs/heads/master@{#452135}
(cherry picked from commit 35848da5131b081ee4751be9669230223baf7c43)
==========

to

==========
Merge M57: "Add metric for tracking media playback utilization."

I.e., how many players completed preload but never saw playback. This
will be handy in terms of guiding efforts to reduce the number of these
types of "useless" players. I.e. maybe deferred offscreen loading, etc.

BUG=694855
TEST=manual

Review-Url: https://codereview.chromium.org/2709903002
Cr-Commit-Position: refs/heads/master@{#452135}
(cherry picked from commit 35848da5131b081ee4751be9669230223baf7c43)

Review-Url: https://codereview.chromium.org/2711803006 .
Cr-Commit-Position: refs/branch-heads/2987@{#667}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/24d1a80b879c17c908312ffdd84c...
==========

[DaleCurtis, 2017-02-23 20:01:20]

Committed patchset #1 (id:1) manually as
24d1a80b879c17c908312ffdd84c8c6b76ad325a.