Fix lifetime of EnhancedBookmarkModel & BookmarkImageService

Fix lifetime of EnhancedBookmarkModel & BookmarkImageService

Unregister BookmarkImageService observer from BookmarkModel in the
Shutdown method instead of the destructor to follow the two step
shutdown of the profile.

Fix a typo in the EnhancedBookmarkModel override of KeyedService
Shutdown method (could have been caught by using the OVERRIDE keyword).

BUG=None

Committed: https://crrev.com/80f52c68fbd705cde1f35866998540fb3e60f126
Cr-Commit-Position: refs/heads/master@{#296009}

[sdefresne, 2014-09-22 16:21:13]

sdefresne@chromium.org changed reviewers:
+ noyau@chromium.org

[sdefresne, 2014-09-22 16:21:14]

PTAL

[noyau (Ping after 24h), 2014-09-22 16:21:51]

The CQ bit was checked by noyau@chromium.org

[noyau (Ping after 24h), 2014-09-22 16:21:51]

lgtm

[commit-bot: I haz the power, 2014-09-22 16:22:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/588233002/1

[commit-bot: I haz the power, 2014-09-22 16:29:14]

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

[commit-bot: I haz the power, 2014-09-22 16:29:15]

Try jobs failed on following builders:
  ios_rel_device on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device/bu...)
  mac_chromium_compile_dbg on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[sdefresne, 2014-09-22 16:47:48]

The CQ bit was checked by sdefresne@chromium.org

[commit-bot: I haz the power, 2014-09-22 16:48:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/588233002/20001

[commit-bot: I haz the power, 2014-09-22 17:49:51]

Committed patchset #2 (id:20001) as b18d07efe95205befd785a38ee40553f2c94e393

[commit-bot: I haz the power, 2014-09-22 17:50:36]

Patchset 2 (id:??) landed as
https://crrev.com/80f52c68fbd705cde1f35866998540fb3e60f126
Cr-Commit-Position: refs/heads/master@{#296009}