Added owner to Net.{Original}ContentLength* histograms

Added owner to Net.{Original}ContentLength* histograms

These histograms are used to analyze the performance of the
data reduction proxy.

BUG=412461
Committed: https://crrev.com/743386c3ef51b4ad86321b3bb5a1332f7093ef17
Cr-Commit-Position: refs/heads/master@{#294284}

[bengr, 2014-09-10 00:46:29]

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

[bengr, 2014-09-10 00:46:30]

asvitkine: all

[Alexei Svitkine (slow), 2014-09-10 13:47:39]

lgtm

[bengr, 2014-09-10 22:35:26]

The CQ bit was checked by bengr@chromium.org

[commit-bot: I haz the power, 2014-09-10 22:51:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/553273002/1

[commit-bot: I haz the power, 2014-09-11 01:29:28]

Committed patchset #1 (id:1) as 3a6600b659624ce254cd000d1923eadd17422365

[commit-bot: I haz the power, 2014-09-11 01:34:18]

Patchset 1 (id:??) landed as
https://crrev.com/743386c3ef51b4ad86321b3bb5a1332f7093ef17
Cr-Commit-Position: refs/heads/master@{#294284}