Fix ProGuard issues after recent NavigationController refactoring

Fix ProGuard issues after recent NavigationController refactoring

Annotate several NavigationController methods used only in testing, and
remove a helper test function that is unused even in tests.

BUG=398263
NOTRY=true

Committed: https://crrev.com/2e9bcdf661d0231880bafc4be33f74b6f6b685a8
Cr-Commit-Position: refs/heads/master@{#294864}

[jdduke (slow), 2014-09-15 18:01:04]

jdduke@chromium.org changed reviewers:
+ aurimas@chromium.org, tedchoc@chromium.org

[jdduke (slow), 2014-09-15 18:01:04]

aurimas@: PTAL.
tedchoc@: Owner approval.

[aurimas (slooooooooow), 2014-09-15 18:03:04]

LGTM thanks for catching this!

[jdduke (slow), 2014-09-15 18:10:46]

On 2014/09/15 18:03:04, aurimas wrote:
> LGTM thanks for catching this!

TBR'ing ted as this is blocking some downstream builds.

[Ted C, 2014-09-15 18:13:23]

lgtm

[jdduke (slow), 2014-09-15 18:18:38]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-09-15 18:25:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/569343002/1

[commit-bot: I haz the power, 2014-09-15 19:16:20]

Committed patchset #1 (id:1) as c75a69967b3e63ce8a163e3df2c1b53b6ede5165

[commit-bot: I haz the power, 2014-09-15 19:21:19]

Patchset 1 (id:??) landed as
https://crrev.com/2e9bcdf661d0231880bafc4be33f74b6f6b685a8
Cr-Commit-Position: refs/heads/master@{#294864}