android envsetup: Stop exporting CHROME_SRC, CURRENT_DIR

android envsetup: Stop exporting CHROME_SRC, CURRENT_DIR, SCRIPT_DIR.

CHROME_SRC is only used inside of envsetup, there's no need to export it.
Depends on https://chrome-internal-review.googlesource.com/159331/

It looks like CURRENT_DIR and SCRIPT_DIR weren't exported intentionally.
Use "local" (which requires putting most of the code in this script in a
function) to make sure they don't make it into the environment that
envsetup is sourced from.

BUG=330631
NOTRY=true
R=yfriedman@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=262292

[Nico, 2014-04-07 22:58:51]

Ignore this for now, apparently not saying "export" doesn't prevent the variable
from being set when this is sourced.

[Nico, 2014-04-07 23:07:56]

Ok, please take a look. (For the bots, the "local" apparently doesn't make a
difference, but for me it does locally.)

[Yaron, 2014-04-07 23:10:23]

lgtm

[Nico, 2014-04-08 02:44:42]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2014-04-08 02:44:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/thakis@chromium.org/222933004/20001

[Nico, 2014-04-08 03:53:56]

Committed patchset #2 manually as r262292 (presubmit successful).