aura: Replace UI-feature GYP flags with switches.

aura: Replace UI-feature GYP flags with switches.

This replaces the aura_show_about_flag_window_mode and
chromeos_legacy_power_button GYP flags with
--aura-force-compact-window-mode and
--aura-legacy-power-button command-line switches.  There is
concern that using compile-time flags to control these
features will greatly increase the workload on the Chrome OS
builders; we apparently currently share Chrome binaries
across all Chrome OS boards with the same architecture.

BUG=109209, 109052, chrome-os-partner:7570
TEST=manual

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=118522

[Ben Goodger (Google), 2012-01-20 00:23:56]

lgtm

[James Cook, 2012-01-20 05:50:35]

LGTM.  Thanks for taking care of this.

[commit-bot: I haz the power, 2012-01-20 15:30:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/derat@chromium.org/9264025/1001

[commit-bot: I haz the power, 2012-01-20 18:11:32]

Try job failure for 9264025-1001 (retry) (retry) (retry) on mac_rel for step
"update".
It's a second try, previously, step "browser_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

Step "update" is always a major failure.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2012-01-20 22:14:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/derat@chromium.org/9264025/13001