Avoid string copies when determining approximate memory usage in RDHI

Avoid string copies when determining approximate memory usage in RDHI

This patch just pulls the lengths out of the request headers and GURL
rather than serializing/copying them and then querying the length.

BUG=664174
Committed: https://crrev.com/26a0f5bf7030a09f679d41532318282b3e8ee47d
Cr-Commit-Position: refs/heads/master@{#432495}

[Charlie Harrison, 2016-11-15 20:24:43]

The CQ bit was checked by csharrison@chromium.org to run a CQ dry run

[Charlie Harrison, 2016-11-15 20:24:59]

csharrison@chromium.org changed reviewers:
+ rdsmith@chromium.org

[Charlie Harrison, 2016-11-15 20:25:00]

rdsmith ptal!

[commit-bot: I haz the power, 2016-11-15 20:25:16]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[mmenke, 2016-11-15 20:28:39]

On 2016/11/15 20:25:00, Charlie Harrison wrote:
> rdsmith ptal!

Random comment:  If you're looking to reduce string copies,
HttpResponseHeaders::Enum* methods could use StringPieces instead, not sure how
many consumers there are that affect a significant number of requests
(HttpStreamParser and URLRequestHttpJob are two, but beyond that, less sure). 
We also do a lot of copying of cookies.

[mmenke, 2016-11-15 20:29:00]

On 2016/11/15 20:28:39, mmenke wrote:
> On 2016/11/15 20:25:00, Charlie Harrison wrote:
> > rdsmith ptal!
> 
> Random comment:  If you're looking to reduce string copies,
> HttpResponseHeaders::Enum* methods could use StringPieces instead, not sure
how
> many consumers there are that affect a significant number of requests
> (HttpStreamParser and URLRequestHttpJob are two, but beyond that, less sure). 
> We also do a lot of copying of cookies.

At least I *think* we do a lot of cookie copying, could be wrong.

[Charlie Harrison, 2016-11-15 20:36:01]

Thx for the pointers. I noticed this in a profile but I'll keep an eye out for
the cases you mentioned!

[commit-bot: I haz the power, 2016-11-15 20:41:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-11-15 20:41:34]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[Randy Smith (Not in Mondays), 2016-11-16 13:07:04]

LGTM.

https://codereview.chromium.org/2503713004/diff/20001/content/browser/loader/...
File content/browser/loader/resource_dispatcher_host_impl.cc (right):

https://codereview.chromium.org/2503713004/diff/20001/content/browser/loader/...
content/browser/loader/resource_dispatcher_host_impl.cc:2335: int header_length
= 0;
Suggestion: Make this declaration string_cost and use the "string_cost += "
idiom regularly below.  It removes a variable (which I think is good all other
things being equal to reduce conceptual complexity) and makes the accumulation
style consistent.  Very much a matter of personal style, so up to you.

[Charlie Harrison, 2016-11-16 13:55:44]

thanks

https://codereview.chromium.org/2503713004/diff/20001/content/browser/loader/...
File content/browser/loader/resource_dispatcher_host_impl.cc (right):

https://codereview.chromium.org/2503713004/diff/20001/content/browser/loader/...
content/browser/loader/resource_dispatcher_host_impl.cc:2335: int header_length
= 0;
On 2016/11/16 13:07:04, Randy Smith - Not in Mondays wrote:
> Suggestion: Make this declaration string_cost and use the "string_cost += "
> idiom regularly below.  It removes a variable (which I think is good all other
> things being equal to reduce conceptual complexity) and makes the accumulation
> style consistent.  Very much a matter of personal style, so up to you.

Done.

[Charlie Harrison, 2016-11-16 13:56:16]

The CQ bit was checked by csharrison@chromium.org

[Charlie Harrison, 2016-11-16 13:56:17]

The patchset sent to the CQ was uploaded after l-g-t-m from rdsmith@chromium.org
Link to the patchset: https://codereview.chromium.org/2503713004/#ps40001
(title: "rdsmith review and fix unit tests")

[commit-bot: I haz the power, 2016-11-16 13:56:31]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-16 15:40:39]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-11-16 15:45:30]

Description was changed from

==========
Avoid string copies when determining approximate memory usage in RDHI

This patch just pulls the lengths out of the request headers and GURL
rather than serializing/copying them and then querying the length.

BUG=664174
==========

to

==========
Avoid string copies when determining approximate memory usage in RDHI

This patch just pulls the lengths out of the request headers and GURL
rather than serializing/copying them and then querying the length.

BUG=664174

Committed: https://crrev.com/26a0f5bf7030a09f679d41532318282b3e8ee47d
Cr-Commit-Position: refs/heads/master@{#432495}
==========

[commit-bot: I haz the power, 2016-11-16 15:45:31]

Patchset 3 (id:??) landed as
https://crrev.com/26a0f5bf7030a09f679d41532318282b3e8ee47d
Cr-Commit-Position: refs/heads/master@{#432495}