[SPDY] Add histograms for flow control stalls

[SPDY] Add histograms for flow control stalls

Refactor flow control logic a bit.

Also change names of related net log events slightly.

BUG=176592
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=195290

[akalin, 2013-04-19 00:54:54]

+rch for review

[akalin, 2013-04-19 00:55:07]

oh, and +jar for histograms stuff

[Ryan Hamilton, 2013-04-19 04:03:04]

lgtm

[jar (doing other things), 2013-04-19 06:22:29]

https://codereview.chromium.org/13872016/diff/1/tools/metrics/histograms/hist...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/13872016/diff/1/tools/metrics/histograms/hist...
tools/metrics/histograms/histograms.xml:1934: Whether an attempt to send a data
frame was stalled by the session flow
I'm not sure whether the enum value "success" means "stalled" or "not".

IMO, you'd be much clearer defining a custom enum, which was simply "stalled
send" "successful send."

Maybe I'm being thick.... but it is generally really nice when the label really
tells you what the bucket means.

[akalin, 2013-04-19 08:21:14]

PTAL

https://codereview.chromium.org/13872016/diff/1/tools/metrics/histograms/hist...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/13872016/diff/1/tools/metrics/histograms/hist...
tools/metrics/histograms/histograms.xml:1934: Whether an attempt to send a data
frame was stalled by the session flow
On 2013/04/19 06:22:29, jar wrote:
> I'm not sure whether the enum value "success" means "stalled" or "not".
> 
> IMO, you'd be much clearer defining a custom enum, which was simply "stalled
> send" "successful send."
> 
> Maybe I'm being thick.... but it is generally really nice when the label
really
> tells you what the bucket means.

Sounds good to me -- I wasn't sure of the best practices re. custom enums in
histograms. How's this? (I changed the semantics of the enums slightly.)

[jar (doing other things), 2013-04-19 17:36:55]

nit: I didn't like using the abbreviation "len" for variables and parts of
variables.... but I was convinced that we "do it a lot in not code"....

so LGTM

[commit-bot: I haz the power, 2013-04-19 18:05:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/akalin@chromium.org/13872016/9002

[akalin, 2013-04-19 21:20:23]

Committed patchset #3 manually as r195290 (presubmit successful).