Remove the use of page id from NavController's GetVisibleEntry.

Remove the use of page id from NavController's GetVisibleEntry.

BUG=369661
TEST=tests stay green

Committed: https://crrev.com/6b988de501639cc9a8f9d40aa25fc44b431de71d
Reverted: https://crrev.com/67d33496116a22ce2244977569314d818525da04

Committed: https://crrev.com/0dca04d9ff641aaba46bfb3281f3ad21e76e0c0b
Cr-Commit-Position: refs/heads/master@{#313115}

[Charlie Reis, 2015-01-23 07:24:12]

creis@chromium.org changed reviewers:
+ creis@chromium.org

[Charlie Reis, 2015-01-23 07:24:13]

The CQ bit was checked by creis@chromium.org

[Charlie Reis, 2015-01-23 07:24:13]

lgtm

[commit-bot: I haz the power, 2015-01-23 07:24:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/850953002/20001

[commit-bot: I haz the power, 2015-01-23 07:41:47]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-23 07:43:22]

Patchset 2 (id:??) landed as
https://crrev.com/6b988de501639cc9a8f9d40aa25fc44b431de71d
Cr-Commit-Position: refs/heads/master@{#312792}

[kochi, 2015-01-23 09:28:47]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/873583004/ by kochi@chromium.org.

The reason for reverting is: The series of changes (r312793, r312792, r312791)
are suspected to break
pushState() related layout tests in Blink.  Might be some of them only affected,
but let me revert all of them.

BUG=451351.

[Avi (use Gerrit), 2015-01-26 20:09:11]

The CQ bit was checked by avi@chromium.org

[commit-bot: I haz the power, 2015-01-26 20:10:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/850953002/40001

[commit-bot: I haz the power, 2015-01-26 20:21:38]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-01-26 20:23:32]

Patchset 3 (id:??) landed as
https://crrev.com/0dca04d9ff641aaba46bfb3281f3ad21e76e0c0b
Cr-Commit-Position: refs/heads/master@{#313115}