Update to localCache should sync with bufferCache

Currently update to localCache is purged immediately while bufferCache
waits till db transaction is complete.  If we access a cache key in the
middle of the two events, localCache would cache the out of date
cache again, any subsequent access to the same cache key would have
invalid data.

This is causing a problem in moderation, for example, 'unhide' won't appear
on the action menu after a 'hide' action untill the page refreshes,

Bug: 64200
Change-Id: I4db8248b493d1b85bcf2230613c47c44a1e5e729
Merge "Update to localCache should sync with bufferCache"