[Android] Add @VisibleForTesting to getMobileFolderId().

[Android] Add @VisibleForTesting to getMobileFolderId().

We no longer use that function.

TBR=tedchoc, ianwen
BUG=424244
Committed: https://crrev.com/4b2564483acc015ade27f0afed45d05c94861199
Cr-Commit-Position: refs/heads/master@{#300737}

[Kibeom Kim (inactive), 2014-10-22 18:49:02]

kkimlabs@chromium.org changed reviewers:
+ ianwen@chromium.org, tedchoc@chromium.org

[Kibeom Kim (inactive), 2014-10-22 18:49:05]

The CQ bit was checked by kkimlabs@chromium.org

[commit-bot: I haz the power, 2014-10-22 18:50:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/674593002/1

[Ian Wen, 2014-10-22 18:54:27]

lgtm

[commit-bot: I haz the power, 2014-10-22 19:03:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-22 19:03:30]

Try jobs failed on following builders:
  android_chromium_gn_compile_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[Kibeom Kim (inactive), 2014-10-22 19:11:54]

The CQ bit was checked by kkimlabs@chromium.org

[commit-bot: I haz the power, 2014-10-22 19:14:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/674593002/1

[commit-bot: I haz the power, 2014-10-22 20:18:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-22 20:20:11]

Patchset 1 (id:??) landed as
https://crrev.com/4b2564483acc015ade27f0afed45d05c94861199
Cr-Commit-Position: refs/heads/master@{#300737}