Fix dependency of //components/enhanced_bookmarks.

Fix dependency of //components/enhanced_bookmarks.

Remove stale #include in bookmark_server_cluster_service.h and remove
the useless dependency on //components/keyed_service/content from the
BUILD.gn file.

BUG=459705
Committed: https://crrev.com/5ca1300cd84fe816764454cfb13f4c91e994e527
Cr-Commit-Position: refs/heads/master@{#359539}

[sdefresne, 2015-11-13 11:37:42]

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

[sdefresne, 2015-11-13 11:37:42]

PTAL

[blundell, 2015-11-13 11:52:37]

lgtm

[sdefresne, 2015-11-13 13:04:35]

The CQ bit was checked by sdefresne@chromium.org

[commit-bot: I haz the power, 2015-11-13 13:04:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1446463002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1446463002/1

[commit-bot: I haz the power, 2015-11-13 13:08:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-13 13:09:11]

Patchset 1 (id:??) landed as
https://crrev.com/5ca1300cd84fe816764454cfb13f4c91e994e527
Cr-Commit-Position: refs/heads/master@{#359539}