Fix a crash about opening a folder that was deleted by sync

Fix a crash about opening a folder that was deleted by sync

If a bookmark is deleted by sync, bookmarkNodeRemoved() will not be
called in EBManager.

BUG=523924
Committed: https://crrev.com/1a13565a349cba0d2f44a3cb9fbb94ccbb9341f9
Cr-Commit-Position: refs/heads/master@{#345125}

[Ian Wen, 2015-08-24 17:44:28]

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

[Kibeom Kim (inactive), 2015-08-24 17:47:48]

lgtm

[Ian Wen, 2015-08-24 17:53:08]

The CQ bit was checked by ianwen@chromium.org

[commit-bot: I haz the power, 2015-08-24 17:53:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1311873002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1311873002/1

[commit-bot: I haz the power, 2015-08-24 18:24:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-24 18:25:30]

Patchset 1 (id:??) landed as
https://crrev.com/1a13565a349cba0d2f44a3cb9fbb94ccbb9341f9
Cr-Commit-Position: refs/heads/master@{#345125}