Don't use base::WorkerPool in the asset_bundle app.

Don't use base::WorkerPool in the asset_bundle app.

WorkerPools can't be shut down, which means that the app's .so can't be
unloaded (which is bad for single process mode, and which is probably
why the asset bundle tests are flakily crashing on the try bots).

So use a SequencedWorkerPool instead (even though we don't care about
sequencing).

R=eseidel@chromium.org, kulakowski@chromium.org, abarth@chromium.org
BUG=Fixes #268

Committed: https://chromium.googlesource.com/external/mojo/+/08c72e1bad0fdaa71bb356749bb9b548ac18a174

[eseidel, 2015-06-24 22:16:09]

abarth is definitely a better reviewer for this than I am.  But in his absence,
lgtm.

[kulakowski, 2015-06-24 22:17:31]

kulakowski@chromium.org changed reviewers:
+ kulakowski@chromium.org

[kulakowski, 2015-06-24 22:17:32]

lgtm

[kulakowski, 2015-06-24 22:19:08]

https://codereview.chromium.org/1206673006/diff/1/services/asset_bundle/main.cc
File services/asset_bundle/main.cc (right):

https://codereview.chromium.org/1206673006/diff/1/services/asset_bundle/main....
services/asset_bundle/main.cc:20: // TODO(vtl): What's the "right" way to choose
the maximum number of threads?
This could maybe be closer to the magical |4| constant.

[viettrungluu, 2015-06-24 22:23:43]

Thanks Eric & George.

https://codereview.chromium.org/1206673006/diff/1/services/asset_bundle/main.cc
File services/asset_bundle/main.cc (right):

https://codereview.chromium.org/1206673006/diff/1/services/asset_bundle/main....
services/asset_bundle/main.cc:20: // TODO(vtl): What's the "right" way to choose
the maximum number of threads?
On 2015/06/24 22:19:08, kulakowski wrote:
> This could maybe be closer to the magical |4| constant.

Done. (Forgot to move the comment after I discovered that I couldn't just
initialize it in the ctor.)

[viettrungluu, 2015-06-24 22:24:08]

Committed patchset #2 (id:20001) manually as
08c72e1bad0fdaa71bb356749bb9b548ac18a174 (presubmit successful).

[abarth-chromium, 2015-06-24 23:53:55]

Thanks!