GN: Set |enable_webvr| in the declare_args() block.

GN: Set |enable_webvr| in the declare_args() block.

This effectively makes it a configurable argument that can be changed by
downstreams and users alike; so far, trying to change it via `gn args'
failed with:

  The variable "enable_webvr" was set as a build argument
  but never appeared in a declare_args() block in any buildfile.

BUG=389343
R=bajones@chromium.org,brettw@chromium.org,dpranke@chromium.org

Committed: https://crrev.com/c699e89f096292539b287b7917441ed19d13a2e9
Cr-Commit-Position: refs/heads/master@{#409083}

[Raphael Kubo da Costa (rakuco), 2016-08-01 12:44:27]

PTAL.

> This effectively makes it a configurable argument that can be changed by
downstreams and users alike

See https://bugs.chromium.org/p/chromium/issues/detail?id=389343#c34 for why one
would want to do that, for example.

[brettw, 2016-08-01 18:20:47]

lgtm

[bajones, 2016-08-01 18:22:41]

LGTM

[Dirk Pranke, 2016-08-01 18:28:13]

lgtm

[Raphael Kubo da Costa (rakuco), 2016-08-01 21:39:15]

The CQ bit was checked by raphael.kubo.da.costa@intel.com

[commit-bot: I haz the power, 2016-08-01 21:39:38]

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, 2016-08-01 22:51:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-01 23:03:47]

Description was changed from

==========
GN: Set |enable_webvr| in the declare_args() block.

This effectively makes it a configurable argument that can be changed by
downstreams and users alike; so far, trying to change it via `gn args'
failed with:

  The variable "enable_webvr" was set as a build argument
  but never appeared in a declare_args() block in any buildfile.

BUG=389343
R=bajones@chromium.org,brettw@chromium.org,dpranke@chromium.org
==========

to

==========
GN: Set |enable_webvr| in the declare_args() block.

This effectively makes it a configurable argument that can be changed by
downstreams and users alike; so far, trying to change it via `gn args'
failed with:

  The variable "enable_webvr" was set as a build argument
  but never appeared in a declare_args() block in any buildfile.

BUG=389343
R=bajones@chromium.org,brettw@chromium.org,dpranke@chromium.org

Committed: https://crrev.com/c699e89f096292539b287b7917441ed19d13a2e9
Cr-Commit-Position: refs/heads/master@{#409083}
==========

[commit-bot: I haz the power, 2016-08-01 23:03:48]

Patchset 1 (id:??) landed as
https://crrev.com/c699e89f096292539b287b7917441ed19d13a2e9
Cr-Commit-Position: refs/heads/master@{#409083}