Don't report DRP request error code UMA when LOAD_BYPASS_PROXY is set.

Don't report DRP request error code UMA when LOAD_BYPASS_PROXY is set.

This fixes a reporting bug with the
DataReductionProxy.RequestCompletionErrorCodes histograms. Previously,
these histograms counted requests that encountered errors when retrying
the request after bypassing the data reduction proxy (e.g. block-once).
This is incorrect because the error did not occur when trying to use the
DRP.

The fix is to ignore requests that completed with the LOAD_BYPASS_PROXY
load flag, since these requests did not use the DRP even if the
proxy_server() in the URLRequest is still set to the DRP.

BUG=454947
Committed: https://crrev.com/fb93bf47152d82d4403f73fc74b4f560255d16ab
Cr-Commit-Position: refs/heads/master@{#314432}

[sclittle, 2015-02-03 21:44:03]

sclittle@chromium.org changed reviewers:
+ bengr@chromium.org

[sclittle, 2015-02-03 21:44:04]

bengr: all

Thanks in advance

[bengr, 2015-02-03 21:54:50]

lgtm

[sclittle, 2015-02-03 21:55:12]

The CQ bit was checked by sclittle@chromium.org

[commit-bot: I haz the power, 2015-02-03 21:56:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/896793004/1

[commit-bot: I haz the power, 2015-02-03 23:28:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-03 23:29:34]

Patchset 1 (id:??) landed as
https://crrev.com/fb93bf47152d82d4403f73fc74b4f560255d16ab
Cr-Commit-Position: refs/heads/master@{#314432}