Rename Net.DailyContentLength_DataReductionProxyEnabled_Unknown.

Rename Net.DailyContentLength_DataReductionProxyEnabled_Unknown.

Net.DailyContentLength_DataReductionProxyEnabled_Unknown is accidentally
tracking 2 separate metrics in the same histogram. It clashes with
the histogram generated by adding the "Unknown" suffix in
Net.DailyContentLength_DataReductionProxyEnabled. Moving both histograms
to a new name and deprecating the old histograms.

Committed: https://crrev.com/8548b8f0558bf516e204cadb0269a8f178a8ab19
Cr-Commit-Position: refs/heads/master@{#344000}

[Not at Google. Contact bengr, 2015-08-17 23:51:02]

kundaji@chromium.org changed reviewers:
+ bengr@chromium.org, isherman@chromium.org

[Not at Google. Contact bengr, 2015-08-17 23:51:24]

isherman:
  tools/metrics/histograms/histograms.xml

bengr:
 
components/data_reduction_proxy/core/browser/data_reduction_proxy_compression_stats.cc

[Ilya Sherman, 2015-08-18 05:25:26]

histograms lgtm

[bengr, 2015-08-18 17:59:56]

lgtm

[Not at Google. Contact bengr, 2015-08-18 19:25:33]

The CQ bit was checked by kundaji@chromium.org

[Not at Google. Contact bengr, 2015-08-18 19:25:33]

The patchset sent to the CQ was uploaded after l-g-t-m from bengr@chromium.org,
isherman@chromium.org
Link to the patchset: https://codereview.chromium.org/1298073002/#ps40001
(title: "Sync to head")

[commit-bot: I haz the power, 2015-08-18 19:25:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1298073002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1298073002/40001

[commit-bot: I haz the power, 2015-08-18 19:35:04]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-08-18 19:36:03]

Patchset 3 (id:??) landed as
https://crrev.com/8548b8f0558bf516e204cadb0269a8f178a8ab19
Cr-Commit-Position: refs/heads/master@{#344000}