[Temp][Android] Make the code work without SDK extras.
[Temp][Android] Make the code work without SDK extras.

Requiring users to manually download Android SDK Extras is a step
backwards for automation.

Part of the fix is in Crosswalk itself, in the
empty_google_play_services_lib.py script.

Here we just make download_sdk_extras.py do nothing instead of timing
out, as Crosswalk's bots set CHROME_HEADLESS=1 but the files this script
tries to fetch are only accessible from Google's network.

Hopefully we can work together with upstream to make the situation
easier to manage.

fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk