(merge m59) media: Add UMA to record whether encrypted media is enabled

(merge m59) media: Add UMA to record whether encrypted media is enabled

The UMA is recorded when requestMediaKeySystemAccess is called on
non-ClearKey key system but will reported at most once per renderer
process.

BUG=711348
TEST=Manually tested

Review-Url: https://codereview.chromium.org/2824643002
Cr-Commit-Position: refs/heads/master@{#465159}
(cherry picked from commit 604168304f0d95d0fbaf3775b2bd4e1a3ab5dab4)

Review-Url: https://codereview.chromium.org/2834653002 .
Cr-Commit-Position: refs/branch-heads/3071@{#85}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/935d9694edaf875ce825a7f8e7e2296c3152cb99

[xhwang, 2017-04-20 16:30:12]

Description was changed from

==========
(merge m59) media: Add UMA to record whether encrypted media is enabled

The UMA is recorded when requestMediaKeySystemAccess is called on
non-ClearKey key system but will reported at most once per renderer
process.

BUG=711348
TEST=Manually tested

Review-Url: https://codereview.chromium.org/2824643002
Cr-Commit-Position: refs/heads/master@{#465159}
(cherry picked from commit 604168304f0d95d0fbaf3775b2bd4e1a3ab5dab4)
==========

to

==========
(merge m59) media: Add UMA to record whether encrypted media is enabled

The UMA is recorded when requestMediaKeySystemAccess is called on
non-ClearKey key system but will reported at most once per renderer
process.

BUG=711348
TEST=Manually tested

Review-Url: https://codereview.chromium.org/2824643002
Cr-Commit-Position: refs/heads/master@{#465159}
(cherry picked from commit 604168304f0d95d0fbaf3775b2bd4e1a3ab5dab4)

Review-Url: https://codereview.chromium.org/2834653002 .
Cr-Commit-Position: refs/branch-heads/3071@{#85}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/935d9694edaf875ce825a7f8e7e2...
==========

[xhwang, 2017-04-20 16:30:15]

Committed patchset #1 (id:1) manually as
935d9694edaf875ce825a7f8e7e2296c3152cb99 (tree was closed).