Disable GN in gyp_chromium.

Android is still broken:
 https://chromegw.corp.google.com/i/clank.tot/builders/clang-clankium-tot-builder/builds/23775/steps/runhooks/logs/stdio 

ERROR [0mat the command-line "--gyp_vars":1:29: Invalid token.
data_reduction_fallback_host%="http://compress.googlezip.net:80/" app_manifest_version_name="clang-clankium-tot-builder 33.0.1728.0" gcc_version="46" app_manifest_version_code="1728000" data_reduction_proxy_probe_url%="http://check.googlezip.net/connect" host_os="linux" component="shared_library" clang="1" spdy_proxy_auth_origin%="https://proxy.googlezip.net:443/" order_text_section="/b/build/slave/clang-clankium-tot-builder/build/src/orderfiles/orderfile.out" spdy_proxy_auth_value%="3c1d997267c567617ffe0e1b1ebbeed71398dd27" target_arch="arm" chrome_build_id="none" fastbuild="1" OS="android" android_app_targets="['../clank/native/framework/clank.gyp:clank', '../clank/native/framework/clank.gyp:devtools_resources', '../clank/native/framework/clank.gyp:chrome_test_apk', '../clank/java/geppetto/uiautomator.gyp:chrome_uiautomator_tests']"
[0m                            ^
[0mI have no idea what this is.
Generating gyp files from GN...
< gclient runhooks
ERROR: process exited with code 2
@@@STEP_FAILURE@@@
FATAL 2 != 88

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/99963007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238519 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238519