roll leveldb to 68

Roll leveldb to r68

Changes relevant to chrome:

* Do not delay for 1 second on shutdown path (issue 125)
* Make InMemoryEnv return a no-op logger
* Added an in-process lock table (issue 120)

BUG=140543
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=161754

[dgrogan, 2012-10-12 21:40:08]

Josh, could you review this?

The IDB tests pass locally, we'll see what the try servers and cq have to say
about the other leveldb users.

[jsbell, 2012-10-12 21:41:23]

lgtm

[commit-bot: I haz the power, 2012-10-12 21:56:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dgrogan@chromium.org/11142002/2001

[commit-bot: I haz the power, 2012-10-13 02:00:27]

Step "update" is always a major failure.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2012-10-13 08:39:39]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dgrogan@chromium.org/11142002/2001

[commit-bot: I haz the power, 2012-10-13 10:21:32]

Change committed as 161754