Add helper gypi for predexing of prebuilt jars.

Add helper gypi for predexing of prebuilt jars.

After https://codereview.chromium.org/12913009/ landed we need to change
the gyp targets that include prebuilt jars. Some of these live in
external repositories.

This adds a helper gypi for those targets so they are configured
correctly. This should also make it easier going forward to update such
targets.

BUG=158821, 224600
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=191299

[nyquist, 2013-03-28 21:11:15]

cjhopman: PTAL

[cjhopman, 2013-03-28 21:17:00]

lgtm

https://codereview.chromium.org/13234002/diff/1/build/java_prebuilt.gypi
File build/java_prebuilt.gypi (right):

https://codereview.chromium.org/13234002/diff/1/build/java_prebuilt.gypi#newc...
build/java_prebuilt.gypi:52: '--ignore=>!(echo >(_inputs) | md5sum)',
The ">(_inputs)" needs to be single quoted or it will break webview.

[commit-bot: I haz the power, 2013-03-28 21:25:39]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/nyquist@chromium.org/13234002/5001

[commit-bot: I haz the power, 2013-03-29 03:09:45]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[commit-bot: I haz the power, 2013-03-29 03:51:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/nyquist@chromium.org/13234002/5001

[commit-bot: I haz the power, 2013-03-29 04:57:00]

Change committed as 191299