add periodic delay in analysis to reduce request processing latency

add periodic delay in analysis to reduce request processing latency

BUG=
R=brianwilkerson@google.com

Committed: https://code.google.com/p/dart/source/detail?r=43127

[danrubel, 2015-01-25 04:59:40]

danrubel@google.com changed reviewers:
+ brianwilkerson@google.com

[scheglov, 2015-01-25 05:15:42]

LGTM

[Brian Wilkerson, 2015-01-25 17:09:09]

As per the e-mail thread, we should at least add a flag to disable the behavior
(and possibly to control the defaults). We should also add comments to make it
easy to find the code that will need to be removed when the underlying problem
has been fixed.

[danrubel, 2015-01-25 21:07:04]

On 2015/01/25 17:09:09, Brian Wilkerson wrote:
> As per the e-mail thread, we should at least add a flag to disable the
behavior
> (and possibly to control the defaults). We should also add comments to make it
> easy to find the code that will need to be removed when the underlying problem
> has been fixed.

Great suggestions. I have added flag and comments, and uploaded mods here.

[Brian Wilkerson, 2015-01-25 21:39:01]

LGTM

[danrubel, 2015-01-26 02:10:42]

Committed patchset #2 (id:20001) manually as 43127 (presubmit successful).