Add a Link header parser.

Add a Link header parser.

This CL adds a parser for Link headers,
that would enable to support them for various features that can benefit from such support.
Resource Hints (and the non-standard hints: dns-prefetch, prefetch, etc) are likely to be the first users.

This is a re-submit of 889883002 which got reverted.

BUG=58456
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189477

[Yoav Weiss, 2015-02-03 17:45:35]

yoav@yoav.ws changed reviewers:
+ mkwst@chromium.org

[Yoav Weiss, 2015-02-03 17:46:58]

https://codereview.chromium.org/889413005/diff/1/Source/core/loader/LinkHeade...
File Source/core/loader/LinkHeader.cpp (right):

https://codereview.chromium.org/889413005/diff/1/Source/core/loader/LinkHeade...
Source/core/loader/LinkHeader.cpp:144: if ((valueEnd == valueStart) || (position
!= end && *position != ';'))
This is the point where an invalid read happened. (*position != ';') was
executed before the (position != end) check, which resulted in an invalid read.
Reversing the order fixes that, and makes ASAN happy.

[Mike West, 2015-02-03 20:14:01]

Great! Did you add a test that exercises this code path?

LGTM if so. :)

[Yoav Weiss, 2015-02-03 20:25:56]

On 2015/02/03 20:14:01, Mike West wrote:
> Great! Did you add a test that exercises this code path?
> 
> LGTM if so. :)

Didn't add a test, but it was caught as part of the unit tests, so I didn't
think one is needed.

Basically, Whenever a parameter value is the last part of the header (so, in
most of the unit tests),  this code path is exercised.

[Mike West, 2015-02-03 20:26:45]

Ah, right. ASAN failure, not "actual" failure. :)

Land it.

[Yoav Weiss, 2015-02-03 20:31:06]

The CQ bit was checked by yoav@yoav.ws

[commit-bot: I haz the power, 2015-02-03 20:32:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/889413005/1

[commit-bot: I haz the power, 2015-02-03 23:03:12]

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

[commit-bot: I haz the power, 2015-02-03 23:03:13]

Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/41093)

[Yoav Weiss, 2015-02-03 23:07:53]

The CQ bit was checked by yoav@yoav.ws

[commit-bot: I haz the power, 2015-02-03 23:08:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/889413005/1

[commit-bot: I haz the power, 2015-02-04 01:43:59]

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

[commit-bot: I haz the power, 2015-02-04 01:43:59]

Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/41139)

[Yoav Weiss, 2015-02-04 08:36:07]

On 2015/02/04 01:43:59, I haz the power (commit-bot) wrote:
> Try jobs failed on following builders:
>   mac_blink_rel on tryserver.blink
>
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/41139)

I don't see this test failure locally. OTOH, it does seem like this test is
crashy all over the place: 
http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpec...

[Yoav Weiss, 2015-02-04 08:36:14]

The CQ bit was checked by yoav@yoav.ws

[commit-bot: I haz the power, 2015-02-04 08:37:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/889413005/1

[commit-bot: I haz the power, 2015-02-04 10:47:44]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=189477