Try to avoid working on zero-height column sets, when possible.

Try to avoid working on zero-height column sets, when possible.

We may end up with an empty column set between two column spanners, if there is
zero-height column content "separating" them.

We typically have no business inside a zero-height column set, since
fragmentation is impossible there. Fragmentation requires a positive
fragmentainer block size to ensure content progression. So keep looking for a
column set that has a height, and use that one instead, as long as its flow
thread start offset is the same as the one we were requested to map to a
column set.

BUG=675100
Review-Url: https://codereview.chromium.org/2631013002
Cr-Commit-Position: refs/heads/master@{#443998}
Committed: https://chromium.googlesource.com/chromium/src/+/cf39aa8ec1f314d198a3caa12922c254e49d1e7c

[mstensho (USE GERRIT), 2017-01-15 13:50:41]

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

[commit-bot: I haz the power, 2017-01-15 13:50:48]

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, 2017-01-15 15:30:46]

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

[commit-bot: I haz the power, 2017-01-15 15:30:47]

Dry run: This issue passed the CQ dry run.

[mstensho (USE GERRIT), 2017-01-16 09:44:23]

Description was changed from

==========
Try to avoid working on zero-height column sets, when possible.

We may end up with an empty column set between two column spanners, if there is
zero-height column content "separating" them.

We typically have no business inside a zero-height column set, since
fragmentation is impossible there. Fragmentation requires a positive
fragmentainer block size to ensure content progression. So keep looking for a
column set that has a height, and use that one instead, as long as its flow
thread offset is the same as the one we were requested to map to a column set.

BUG=675100
==========

to

==========
Try to avoid working on zero-height column sets, when possible.

We may end up with an empty column set between two column spanners, if there is
zero-height column content "separating" them.

We typically have no business inside a zero-height column set, since
fragmentation is impossible there. Fragmentation requires a positive
fragmentainer block size to ensure content progression. So keep looking for a
column set that has a height, and use that one instead, as long as its flow
thread start offset is the same as the one we were requested to map to a
column set.

BUG=675100
==========

[mstensho (USE GERRIT), 2017-01-16 09:46:01]

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

[mstensho (USE GERRIT), 2017-01-16 09:46:01]

Magic. :/

[eae, 2017-01-17 02:53:23]

LGTM

[mstensho (USE GERRIT), 2017-01-17 06:06:21]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2017-01-17 06:06:32]

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, 2017-01-17 07:21:41]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484633181265690, "parent_rev":
"9cdfb75541aff89b46bdfe92becc92872cb497fd", "commit_rev":
"cf39aa8ec1f314d198a3caa12922c254e49d1e7c"}

[commit-bot: I haz the power, 2017-01-17 07:22:26]

Description was changed from

==========
Try to avoid working on zero-height column sets, when possible.

We may end up with an empty column set between two column spanners, if there is
zero-height column content "separating" them.

We typically have no business inside a zero-height column set, since
fragmentation is impossible there. Fragmentation requires a positive
fragmentainer block size to ensure content progression. So keep looking for a
column set that has a height, and use that one instead, as long as its flow
thread start offset is the same as the one we were requested to map to a
column set.

BUG=675100
==========

to

==========
Try to avoid working on zero-height column sets, when possible.

We may end up with an empty column set between two column spanners, if there is
zero-height column content "separating" them.

We typically have no business inside a zero-height column set, since
fragmentation is impossible there. Fragmentation requires a positive
fragmentainer block size to ensure content progression. So keep looking for a
column set that has a height, and use that one instead, as long as its flow
thread start offset is the same as the one we were requested to map to a
column set.

BUG=675100

Review-Url: https://codereview.chromium.org/2631013002
Cr-Commit-Position: refs/heads/master@{#443998}
Committed:
https://chromium.googlesource.com/chromium/src/+/cf39aa8ec1f314d198a3caa12922...
==========

[commit-bot: I haz the power, 2017-01-17 07:22:26]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/cf39aa8ec1f314d198a3caa12922...