Added some basic WebVR use counters

Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything to that hardware, and how many use a deprecated function call.

BUG=389343
Committed: https://crrev.com/b79b06ddf6ebbe947b820f3d59d6a6cede5d5223
Cr-Commit-Position: refs/heads/master@{#419114}

[bajones, 2016-09-15 20:05:33]

Description was changed from

==========
Added some basic WebVR use counters

BUG=389343
==========

to

==========
Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything
to that hardware, and how many use a deprecated function call.

BUG=389343
==========

[bajones, 2016-09-15 20:05:37]

bajones@chromium.org changed reviewers:
+ haraken@chromium.org, mpearson@chromium.org

[bajones, 2016-09-15 20:05:38]

mpearson@: Review histograms.xml please?

haraken@: core/ and source/ please?

[Mark P, 2016-09-15 21:54:43]

histograms.xml lgtm

[haraken, 2016-09-16 01:51:19]

modules/ LGTM

[bajones, 2016-09-16 03:30:38]

bajones@chromium.org changed reviewers:
+ mkwst@chromium.org

[bajones, 2016-09-16 03:30:39]

mkwst@chromium.org: Please review changes in UseCounter.h

[Mike West, 2016-09-16 05:05:34]

LGTM

[bajones, 2016-09-16 05:06:09]

The CQ bit was checked by bajones@chromium.org

[commit-bot: I haz the power, 2016-09-16 05:06:30]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-16 06:46:56]

Description was changed from

==========
Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything
to that hardware, and how many use a deprecated function call.

BUG=389343
==========

to

==========
Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything
to that hardware, and how many use a deprecated function call.

BUG=389343
==========

[commit-bot: I haz the power, 2016-09-16 06:46:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-16 06:49:58]

Description was changed from

==========
Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything
to that hardware, and how many use a deprecated function call.

BUG=389343
==========

to

==========
Added some basic WebVR use counters

Tracking how many pages query for VR hardware, how many actually pesent anything
to that hardware, and how many use a deprecated function call.

BUG=389343

Committed: https://crrev.com/b79b06ddf6ebbe947b820f3d59d6a6cede5d5223
Cr-Commit-Position: refs/heads/master@{#419114}
==========

[commit-bot: I haz the power, 2016-09-16 06:50:00]

Patchset 1 (id:??) landed as
https://crrev.com/b79b06ddf6ebbe947b820f3d59d6a6cede5d5223
Cr-Commit-Position: refs/heads/master@{#419114}