Add HTTP Peer to DownloadSources enumeration

Add HTTP Peer to DownloadSources enumeration

This way the Installer.DownloadSourcesUsed metric conveys how often
p2p is used and new metrics Installer.SuccessfulMBsDownloadedFromHttpPeer
and Installer.TotalMBsDownloadedFromHttpPeer gives additional detail.

BUG=chromium:284714
TEST=Validated the xml, pretty print succeeded.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=221214

[zeuthen, 2013-09-03 21:09:06]

Thanks for the review. The corresponding code change for the ChromeOS
update_engine is here: https://chromium-review.googlesource.com/#/c/167913/

[Ilya Sherman, 2013-09-03 22:43:23]

histograms.xml lgtm

https://codereview.chromium.org/23838003/diff/1/tools/metrics/histograms/hist...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/23838003/diff/1/tools/metrics/histograms/hist...
tools/metrics/histograms/histograms.xml:25140: +  <int value="3" label="HTTP
Server, HTTPS Server"/>
nit: IMO "and" would be clearer than a comma, here and below, but it's fine to
keep this as-is if you prefer this way.

[zeuthen, 2013-09-04 01:00:27]

On 2013/09/03 22:43:23, Ilya Sherman wrote:
> nit: IMO "and" would be clearer than a comma, here and below, but it's fine to
> keep this as-is if you prefer this way.

I agree, I'll add the "and"! Thanks for the review!

[commit-bot: I haz the power, 2013-09-04 01:14:39]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zeuthen@chromium.org/23838003/6001

[commit-bot: I haz the power, 2013-09-04 17:17:10]

Change committed as 221214

[zeuthen, 2013-09-10 00:02:34]

Ooops, sorry for the noise. Hit the wrong button.