[Spellcheck] Add UMA stat for SpellingService

[Spellcheck] Add UMA stat for SpellingService

R=rlp@chromium.org
BUG=177308
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=184096

[rpetterson, 2013-02-21 22:01:06]

LGTM

Just a small question about the test.

https://codereview.chromium.org/12335019/diff/1/chrome/browser/spellchecker/s...
File chrome/browser/spellchecker/spellcheck_host_metrics_unittest.cc (right):

https://codereview.chromium.org/12335019/diff/1/chrome/browser/spellchecker/s...
chrome/browser/spellchecker/spellcheck_host_metrics_unittest.cc:133: if
(histogram)
When would this not be here? Or rather, why use "if" as opposed to ASSERT?

[groby-ooo-7-16, 2013-02-22 04:32:29]

https://codereview.chromium.org/12335019/diff/1/chrome/browser/spellchecker/s...
File chrome/browser/spellchecker/spellcheck_host_metrics_unittest.cc (right):

https://codereview.chromium.org/12335019/diff/1/chrome/browser/spellchecker/s...
chrome/browser/spellchecker/spellcheck_host_metrics_unittest.cc:133: if
(histogram)
On 2013/02/21 22:01:06, rpetterson wrote:
> When would this not be here? Or rather, why use "if" as opposed to ASSERT?

If no counts for this histogram have been recorded yet, histogram will be NULL.
This happens _only_ if this is the very first test accessing the stat.
Unfortunately, histogram state can't be easily reset and survives until the
process gets shut down.  If _any_ other unit tests added to that histogram, we
get a non-NULL pointer.

That means both cases are valid, hence no ASSERT.

[commit-bot: I haz the power, 2013-02-22 04:33:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/groby@chromium.org/12335019/1

[commit-bot: I haz the power, 2013-02-22 11:37:31]

Change committed as 184096