Make content_extractor support a multiple-url request

Make content_extractor support a multiple-url request

This adds the --urls flag which accepts a space-separated list of urls
to distill.

This adds a pretty straightforward approach to having multiple of these
requests happening at the same time.

Once all requests are finished, they will be printed (in the order that
they appeared in --urls). If printing binary, each serialized protobuf
will be preceded by its size (as a varint32).

TBR=ben@

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276819

[Yaron, 2014-05-13 18:14:30]

lgtm

https://codereview.chromium.org/276553002/diff/1/components/dom_distiller/sta...
File components/dom_distiller/standalone/content_extractor.cc (right):

https://codereview.chromium.org/276553002/diff/1/components/dom_distiller/sta...
components/dom_distiller/standalone/content_extractor.cc:150: ADD_FAILURE() <<
"Bad url";
 << i << ": " << url.spec()

https://codereview.chromium.org/276553002/diff/1/components/dom_distiller/sta...
components/dom_distiller/standalone/content_extractor.cc:246: --pending_tasks_;
output something to indicate some level of progress? Otherwise if you'd doing
like a hundred pages you have no feedback until they're all done, right? Should
be easy to filter out from response, no?

[cjhopman, 2014-06-12 17:38:43]

TBR ben@ for adding google/ to DEPS

[cjhopman, 2014-06-12 17:38:46]

The CQ bit was checked by cjhopman@chromium.org

[commit-bot: I haz the power, 2014-06-12 17:40:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/cjhopman@chromium.org/276553002/30001

[commit-bot: I haz the power, 2014-06-12 22:02:33]

Change committed as 276819