chrome/installer: Fix the cros chrome-sdk build.

The target chrome/installer/linux:calculate_deb_dependencies is broken
in the cros chrome-sdk shell build because is_linux is true in addition
to is_chromeos.

This change prevents the linux installer from being enabled when
is_chromeos is true.

R=gab@chromium.org

Bug: 867013
Test: none
Change-Id: I1596177528c35a4670fad52e62d56ad0ba104a16
Reviewed-on: https://chromium-review.googlesource.com/1150443
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: James Hawkins <jhawkins@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578336}
1 file changed