Increase timer slack for several browser threads.

Increase timer slack for several browser threads.

Set timer slack to maximal value for the following browser threads:
* WatchdogThread
* DB Thread
* File thread
* Process Launcher thread
* Cache thread

BUG=356804
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280138

[jeremy, 2014-06-26 12:55:58]

This CL increases slack for a bunch of browser threads we've identified as being
potentially coalescible.  The plan is to land this, monitor the perf graphs and
if nothing regresses then do another batch.

Mark: review please.
Jochen: Owner review, rubberstamp OK

[Mark Mentovai, 2014-06-26 13:05:11]

LGTM

[jochen (gone - plz use gerrit), 2014-06-26 14:50:52]

lgtm

[jeremy, 2014-06-26 16:28:46]

The CQ bit was checked by jeremy@chromium.org

[commit-bot: I haz the power, 2014-06-26 16:29:15]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jeremy@chromium.org/351223002/1

[commit-bot: I haz the power, 2014-06-26 20:07:51]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-06-26 22:36:35]

Change committed as 280138

[pasko, 2014-06-27 15:50:28]

Can you reference results of your testing in the description of this change?

Frankly, my first reaction is: "Don't do this for the cache thread!". The cache
thread is on the critical path to resource fetching, adding extra slack will
likely affect page loading latency for users.

This should not affect Android because the use of the cache thread in
simplecache is limited.