Update gn_all, gyp_remaining for chromeos.

Update gn_all, gyp_remaining for chromeos.

This involves restructuring the remoting conditionals in gn_all and
gyp_remaining a fair amount, but otherwise no real surprises here.
There are a few chromeos-specific unittest targets in content that
we still need to port, but otherwise the port is as complete as desktop
linux.

BUG=433082
Committed: https://crrev.com/6293d2503965332696a292ff8a8da0a8f2a7ecc5
Cr-Commit-Position: refs/heads/master@{#325097}

[Dirk Pranke, 2015-04-09 02:50:45]

This patch depends on the win gn_all/gyp_remaining patch that was reverted, so
it won't work on its own.

[Dirk Pranke, 2015-04-14 02:36:59]

The CQ bit was checked by dpranke@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-14 02:37:09]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1069903002/40001

[commit-bot: I haz the power, 2015-04-14 02:45:17]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-14 02:45:19]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[tfarina, 2015-04-14 13:40:04]

tfarina@chromium.org changed reviewers:
+ tfarina@chromium.org

[tfarina, 2015-04-14 13:40:04]

lgtm

[Dirk Pranke, 2015-04-14 17:19:16]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2015-04-14 17:20:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1069903002/40001

[commit-bot: I haz the power, 2015-04-14 19:12:12]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-04-14 19:13:36]

Patchset 3 (id:??) landed as
https://crrev.com/6293d2503965332696a292ff8a8da0a8f2a7ecc5
Cr-Commit-Position: refs/heads/master@{#325097}