Clean up default toolchain logic for CrOS GN builds.

Clean up default toolchain logic for CrOS GN builds.

The initial versions of the CrOS GN builds were written when we
didn't really understand how the different CrOS builds would work,
and we weren't sure what the toolchains needed to look like.

We can now safely say that the //build/toolchain/cros:* toolchains
should only be used in the simplechrome and ebuild workflows, where
`custom_toolchain="//build/toolchain/cros:target"` in the GN args.
For "regular" desktop ChromeOS builds, we should just re-use the
linux toolchains.

R=brettw@chromium.org, llozano@chromium.org
BUG=632279
Committed: https://crrev.com/d5b49c1cf6737a33c918e8433c12e19538223f6e
Cr-Commit-Position: refs/heads/master@{#409652}

[brettw, 2016-08-03 22:12:46]

lgtm

[Dirk Pranke, 2016-08-03 22:13:33]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2016-08-03 22:14:07]

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, 2016-08-03 23:08:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-03 23:10:40]

Description was changed from

==========
Clean up default toolchain logic for CrOS GN builds.

The initial versions of the CrOS GN builds were written when we
didn't really understand how the different CrOS builds would work,
and we weren't sure what the toolchains needed to look like.

We can now safely say that the //build/toolchain/cros:* toolchains
should only be used in the simplechrome and ebuild workflows, where
`custom_toolchain="//build/toolchain/cros:target"` in the GN args.
For "regular" desktop ChromeOS builds, we should just re-use the
linux toolchains.

R=brettw@chromium.org, llozano@chromium.org
BUG=632279
==========

to

==========
Clean up default toolchain logic for CrOS GN builds.

The initial versions of the CrOS GN builds were written when we
didn't really understand how the different CrOS builds would work,
and we weren't sure what the toolchains needed to look like.

We can now safely say that the //build/toolchain/cros:* toolchains
should only be used in the simplechrome and ebuild workflows, where
`custom_toolchain="//build/toolchain/cros:target"` in the GN args.
For "regular" desktop ChromeOS builds, we should just re-use the
linux toolchains.

R=brettw@chromium.org, llozano@chromium.org
BUG=632279

Committed: https://crrev.com/d5b49c1cf6737a33c918e8433c12e19538223f6e
Cr-Commit-Position: refs/heads/master@{#409652}
==========

[commit-bot: I haz the power, 2016-08-03 23:10:41]

Patchset 1 (id:??) landed as
https://crrev.com/d5b49c1cf6737a33c918e8433c12e19538223f6e
Cr-Commit-Position: refs/heads/master@{#409652}