Adding ExperimentLabels helper class.

Adding ExperimentLabels helper class.

This new class provides basic operations on an Omaha experiment_labels
value. It will be used in subsequent changes.

BUG=717091
Review-Url: https://codereview.chromium.org/2872583002
Cr-Commit-Position: refs/heads/master@{#470147}
Committed: https://chromium.googlesource.com/chromium/src/+/d5843c47cf797621cfc476c9914f8cb5ce258e88

[grt (UTC plus 2), 2017-05-08 11:42:23]

grt@chromium.org changed reviewers:
+ pmonette@chromium.org

[grt (UTC plus 2), 2017-05-08 11:42:23]

This is the first CL for the Win 10 user retention experiment. PTAL.

[grt (UTC plus 2), 2017-05-08 11:43:07]

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

[commit-bot: I haz the power, 2017-05-08 11:43:19]

Dry run: 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, 2017-05-08 13:32:05]

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

[commit-bot: I haz the power, 2017-05-08 13:32:06]

Dry run: This issue passed the CQ dry run.

[Patrick Monette, 2017-05-08 15:27:49]

LGTM with few nits!

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels.cc (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:48: // |lifetime| into the future.
Rewrite comment to use |expiration| instead of |lifetime|.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:53: // "Fri, 14 Aug 2015 16:13:03
GMT"
It's weird that Omaha uses 4 digits for the year, but
http://www.ietf.org/rfc/rfc822.txt
specifies 2 digits. Not your fault though!

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:66: base::string16* label) {
Is it possible to use reserve() here?

Maybe not given that the time format size can differ for 1 or 2 characters.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels.h (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:28: base::StringPiece16
GetValueForLabel(base::StringPiece16 label_name) const;
Maybe note that ExperimentLabels must outlive the StringPiece returned?

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:33: // extended to delete if
|lifetime| is zero.
I'm not a fan of this comment. If this is ever needed, there's a good chance I'd
recommend an explicit DeleteValue() function, depending on the use-case.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:44: // A label's full contents
("name=value|exp") and value within |value_|.
s/exp/expiration

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:47: // Returns the label and value
nameed |label_name|, or empty string pieces if
s/nameed/named

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels_unittest.cc (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels_unittest.cc:18: TEST(ExperimentLabels,
value) {
s/value/Value?

I have never seen a test name with a lower case name.

[grt (UTC plus 2), 2017-05-08 20:15:26]

Thanks!

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels.cc (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:48: // |lifetime| into the future.
On 2017/05/08 15:27:48, Patrick Monette wrote:
> Rewrite comment to use |expiration| instead of |lifetime|.

Done.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:53: // "Fri, 14 Aug 2015 16:13:03
GMT"
On 2017/05/08 15:27:48, Patrick Monette wrote:
> It's weird that Omaha uses 4 digits for the year, but
> http://www.ietf.org/rfc/rfc822.txt
> specifies 2 digits. Not your fault though!

Hmm, yeah. I've added pointers to the relevant Omaha code.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.cc:66: base::string16* label) {
On 2017/05/08 15:27:48, Patrick Monette wrote:
> Is it possible to use reserve() here?

Yes We Can!

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels.h (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:28: base::StringPiece16
GetValueForLabel(base::StringPiece16 label_name) const;
On 2017/05/08 15:27:48, Patrick Monette wrote:
> Maybe note that ExperimentLabels must outlive the StringPiece returned?

Done.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:33: // extended to delete if
|lifetime| is zero.
On 2017/05/08 15:27:48, Patrick Monette wrote:
> I'm not a fan of this comment. If this is ever needed, there's a good chance
I'd
> recommend an explicit DeleteValue() function, depending on the use-case.

Funny, I had the same thought earlier today -- it'd be a clunky interface. Done.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:44: // A label's full contents
("name=value|exp") and value within |value_|.
On 2017/05/08 15:27:48, Patrick Monette wrote:
> s/exp/expiration

Done.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels.h:47: // Returns the label and value
nameed |label_name|, or empty string pieces if
On 2017/05/08 15:27:48, Patrick Monette wrote:
> s/nameed/named

Nice catch! Done.

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
File chrome/installer/util/experiment_labels_unittest.cc (right):

https://codereview.chromium.org/2872583002/diff/1/chrome/installer/util/exper...
chrome/installer/util/experiment_labels_unittest.cc:18: TEST(ExperimentLabels,
value) {
On 2017/05/08 15:27:48, Patrick Monette wrote:
> s/value/Value?
> 
> I have never seen a test name with a lower case name.

Done. I did that 'cause the method it is testing is lower-case. I guess it does
look odd.

[grt (UTC plus 2), 2017-05-08 20:16:44]

The CQ bit was checked by grt@chromium.org

[grt (UTC plus 2), 2017-05-08 20:16:45]

The patchset sent to the CQ was uploaded after l-g-t-m from
pmonette@chromium.org
Link to the patchset: https://codereview.chromium.org/2872583002/#ps20001
(title: "pmonette comments")

[commit-bot: I haz the power, 2017-05-08 20:17:25]

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, 2017-05-08 22:09:59]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1494274604932270,
"parent_rev": "3aa41d205d3efc87258a59e4db771ba9cabee9c2", "commit_rev":
"d5843c47cf797621cfc476c9914f8cb5ce258e88"}

[commit-bot: I haz the power, 2017-05-08 22:10:56]

Description was changed from

==========
Adding ExperimentLabels helper class.

This new class provides basic operations on an Omaha experiment_labels
value. It will be used in subsequent changes.

BUG=717091
==========

to

==========
Adding ExperimentLabels helper class.

This new class provides basic operations on an Omaha experiment_labels
value. It will be used in subsequent changes.

BUG=717091

Review-Url: https://codereview.chromium.org/2872583002
Cr-Commit-Position: refs/heads/master@{#470147}
Committed:
https://chromium.googlesource.com/chromium/src/+/d5843c47cf797621cfc476c9914f...
==========

[commit-bot: I haz the power, 2017-05-08 22:10:58]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/d5843c47cf797621cfc476c9914f...