Consistent pagination strut propagation policies.

Consistent pagination strut propagation policies.

There's no break opportunity between a spanner and the next block in a column.
Also no break opportunity between a float and an in-flow block. The spec is a
bit vague here, but our implementation certainly doesn't support it.

We have to prevent strut propagation in such cases. If the first piece of
content inside the block (e.g. a line) doesn't fit inside the current
fragmentainer, it's the line that needs to be pushed, not the block.

One of the tests included here used to cause a DCHECK failure.

Review-Url: https://codereview.chromium.org/2746013010
Cr-Commit-Position: refs/heads/master@{#457888}
Committed: https://chromium.googlesource.com/chromium/src/+/d79ffe1a26f9a6f9572cff9c2e5f12a119032c64

[mstensho (USE GERRIT), 2017-03-17 15:42:21]

The CQ bit was checked by mstensho@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-03-17 15:42:53]

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, 2017-03-17 16:19:30]

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

[commit-bot: I haz the power, 2017-03-17 16:19:31]

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

[mstensho (USE GERRIT), 2017-03-17 18:31:21]

The CQ bit was checked by mstensho@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-03-17 18:31:44]

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, 2017-03-17 19:43:47]

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

[commit-bot: I haz the power, 2017-03-17 19:43:48]

Dry run: This issue passed the CQ dry run.

[mstensho (USE GERRIT), 2017-03-17 20:23:55]

mstensho@opera.com changed reviewers:
+ eae@chromium.org

[eae, 2017-03-17 20:46:13]

Code change LGTM and I do like the new tests!
Out of curiosity, which DCHECK did it use to hit?

[mstensho (USE GERRIT), 2017-03-17 20:58:06]

On 2017/03/17 20:46:13, eae wrote:
> Code change LGTM and I do like the new tests!
> Out of curiosity, which DCHECK did it use to hit?

LayoutTests/fast/multicol/span/outer-column-break-after-inner-spanner-2.html
failed at minSpaceShortage != LayoutUnit::max() in
MultiColumnFragmentainerGroup::rebalanceColumnHeightIfNeeded(), meaning that
some column row overflowed (i.e. got a higher actual-value of column-count than
its used-value when it was given a balanced column height), and then we failed
to stretch it for the contents to fit. This test was also rendered incorrectly
when tested in builds with DCHECK disabled.

[eae, 2017-03-17 20:59:51]

Ah, that makes sense. Thanks for clarifying!

LGTM

[mstensho (USE GERRIT), 2017-03-17 21:18:24]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2017-03-17 21:18:58]

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, 2017-03-17 21:26:43]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489785504295230, "parent_rev":
"781ec99312269de798d55435b8576ed882b0f57b", "commit_rev":
"d79ffe1a26f9a6f9572cff9c2e5f12a119032c64"}

[commit-bot: I haz the power, 2017-03-17 21:27:41]

Description was changed from

==========
Consistent pagination strut propagation policies.

There's no break opportunity between a spanner and the next block in a column.
Also no break opportunity between a float and an in-flow block. The spec is a
bit vague here, but our implementation certainly doesn't support it.

We have to prevent strut propagation in such cases. If the first piece of
content inside the block (e.g. a line) doesn't fit inside the current
fragmentainer, it's the line that needs to be pushed, not the block.

One of the tests included here used to cause a DCHECK failure.
==========

to

==========
Consistent pagination strut propagation policies.

There's no break opportunity between a spanner and the next block in a column.
Also no break opportunity between a float and an in-flow block. The spec is a
bit vague here, but our implementation certainly doesn't support it.

We have to prevent strut propagation in such cases. If the first piece of
content inside the block (e.g. a line) doesn't fit inside the current
fragmentainer, it's the line that needs to be pushed, not the block.

One of the tests included here used to cause a DCHECK failure.

Review-Url: https://codereview.chromium.org/2746013010
Cr-Commit-Position: refs/heads/master@{#457888}
Committed:
https://chromium.googlesource.com/chromium/src/+/d79ffe1a26f9a6f9572cff9c2e5f...
==========

[commit-bot: I haz the power, 2017-03-17 21:27:42]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d79ffe1a26f9a6f9572cff9c2e5f...