Added UMA to track ExtensionService::Init time.

Added UMA to track ExtensionService::Init time.

This functions is called every time a profile is loaded, including
during startup.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=235679

[benwells, 2013-11-14 03:08:33]

koz for sanity

[koz (OOO until 15th September), 2013-11-14 03:41:24]

lgtm

https://codereview.chromium.org/62953020/diff/30001/chrome/browser/extensions...
File chrome/browser/extensions/extension_service.cc (right):

https://codereview.chromium.org/62953020/diff/30001/chrome/browser/extensions...
chrome/browser/extensions/extension_service.cc:593:
UMA_HISTOGRAM_TIMES("Extensions.ExtensionServiceInit",
It's common to have a Time suffix if you are measuring the duration of
something.

https://codereview.chromium.org/62953020/diff/30001/tools/metrics/histograms/...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/62953020/diff/30001/tools/metrics/histograms/...
tools/metrics/histograms/histograms.xml:4353: +    Time for the ExtensionService
to initialize, including the time it takes to
s/Time for/Time taken for/

[benwells, 2013-11-15 00:08:32]

+cc jeremy fyi
+jar for histograms

[jar (doing other things), 2013-11-15 06:31:44]

histograms.xml LGTM

[commit-bot: I haz the power, 2013-11-15 07:47:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/benwells@chromium.org/62953020/80001

[commit-bot: I haz the power, 2013-11-15 09:37:54]

Retried try job too often on win_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2013-11-18 06:01:59]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/benwells@chromium.org/62953020/80001

[commit-bot: I haz the power, 2013-11-18 09:32:26]

Change committed as 235679