Update leveldb to reuse-manifest/HEAD

Update leveldb to reuse-manifest/HEAD

BUG=505316
Committed: https://crrev.com/bbb4c551cb0e5a2c0783ff5218873da813d57a8d
Cr-Commit-Position: refs/heads/master@{#354086}

[cmumford, 2015-10-14 15:54:45]

cmumford@chromium.org changed reviewers:
+ jsbell@chromium.org

[jsbell, 2015-10-14 16:56:52]

Can you update third_party/leveldatabase/README as well? the r80 is obsolete,
and including the branch/commit would be helpful.

(Especially the branch, so someone else doesn't ever accidentally try and move
us to master before the branch is merged.)

Calling out why we're using a branch in the README might also be a good idea.

[cmumford, 2015-10-14 18:14:15]

Added branch notes to README.chromium

[jsbell, 2015-10-14 18:25:08]

lgtm

[cmumford, 2015-10-14 18:33:20]

The CQ bit was checked by cmumford@chromium.org

[commit-bot: I haz the power, 2015-10-14 18:35:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1395873003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1395873003/20001

[commit-bot: I haz the power, 2015-10-14 19:41:17]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-14 19:42:13]

Patchset 2 (id:??) landed as
https://crrev.com/bbb4c551cb0e5a2c0783ff5218873da813d57a8d
Cr-Commit-Position: refs/heads/master@{#354086}