Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Note: The original patch was reviewed and submitted in
https://codereview.chromium.org/2733133002/
The only difference with the original patch is that
NGExclusion::MaybeCombineWith doesn't have NOTREACHED anymore. That's
because some tests and text exclusions don't have exclusion.type set.
We just return false in this case.

This patch introduces the logic that tries to combine 2 exclusions if
possible.
We can combine 2 exclusions if
 - they are adjoining to each other and have the same exclusion type
 - the new exclusion shadows the old one.
   That's because it's not allowed to position anything in the
   shadowed area.

Example:
 <div id="SS" style="float: left; height: 10px; width: 10px"></div>
 <div id="BB" style="float: left; height: 20px; width: 20px"></div>
 +----------------+
 |SSBB
 |**BB
 We combine SS and BB exclusions including the shadowed area (**).

BUG=635619, 699703
TESTS=TwoRightExclusionsShadowEachOther,
TwoLeftExclusionsShadowEachOther

Review-Url: https://codereview.chromium.org/2743453002
Cr-Commit-Position: refs/heads/master@{#455876}
Committed: https://chromium.googlesource.com/chromium/src/+/875a510c97b3108d5ca70c7878c9a3a3d3830fd0

[Gleb Lanbin, 2017-03-08 21:59:17]

glebl@chromium.org changed reviewers:
+ ikilpatrick@chromium.org

[Gleb Lanbin, 2017-03-08 21:59:25]

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

[commit-bot: I haz the power, 2017-03-08 21:59:44]

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

[Gleb Lanbin, 2017-03-08 22:00:04]

Description was changed from

==========
Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Note: The original patch was reviewed and submitted in
https://codereview.chromium.org/2733133002/
The only difference with the original patch is that
NGExclusion::MaybeCombineWith doesn't have NOTREACHED anymore. That's
because some tests and text exclusions don't have exclusion.type set.
We just return false in this case.

This patch introduces the logic that tries to combine 2 exclusions if
possible.
We can combine 2 exclusions if
 - they are adjoining to each other and have the same exclusion type
 - the new exclusion shadows the old one.
   That's because it's not allowed to position anything in the
   shadowed area.

Example:
 <div id="SS" style="float: left; height: 10px; width: 10px"></div>
 <div id="BB" style="float: left; height: 20px; width: 20px"></div>
 +----------------+
 |SSBB
 |**BB
 We combine SS and BB exclusions including the shadowed area (**).

BUG=635619,699703
TESTS=TwoRightExclusionsShadowEachOther,
TwoLeftExclusionsShadowEachOther
==========

to

==========
Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Note: The original patch was reviewed and submitted in
https://codereview.chromium.org/2733133002/
The only difference with the original patch is that
NGExclusion::MaybeCombineWith doesn't have NOTREACHED anymore. That's
because some tests and text exclusions don't have exclusion.type set.
We just return false in this case.

This patch introduces the logic that tries to combine 2 exclusions if
possible.
We can combine 2 exclusions if
 - they are adjoining to each other and have the same exclusion type
 - the new exclusion shadows the old one.
   That's because it's not allowed to position anything in the
   shadowed area.

Example:
 <div id="SS" style="float: left; height: 10px; width: 10px"></div>
 <div id="BB" style="float: left; height: 20px; width: 20px"></div>
 +----------------+
 |SSBB
 |**BB
 We combine SS and BB exclusions including the shadowed area (**).

BUG=635619,699703
TESTS=TwoRightExclusionsShadowEachOther,
TwoLeftExclusionsShadowEachOther
==========

[Gleb Lanbin, 2017-03-08 22:00:04]

glebl@chromium.org changed reviewers:
+ cbiesinger@chromium.org

[commit-bot: I haz the power, 2017-03-09 00:00:47]

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

[commit-bot: I haz the power, 2017-03-09 00:00:48]

Dry run: This issue passed the CQ dry run.

[ikilpatrick, 2017-03-09 21:51:19]

lgtm

[cbiesinger, 2017-03-09 21:55:30]

lgtm

[Gleb Lanbin, 2017-03-09 21:56:33]

The CQ bit was checked by glebl@chromium.org

[commit-bot: I haz the power, 2017-03-09 21:57:19]

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, 2017-03-09 22:04:17]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489096593578710, "parent_rev":
"30557b1a00d4cf8daca845404ae6951c8089d01c", "commit_rev":
"875a510c97b3108d5ca70c7878c9a3a3d3830fd0"}

[commit-bot: I haz the power, 2017-03-09 22:05:01]

Description was changed from

==========
Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Note: The original patch was reviewed and submitted in
https://codereview.chromium.org/2733133002/
The only difference with the original patch is that
NGExclusion::MaybeCombineWith doesn't have NOTREACHED anymore. That's
because some tests and text exclusions don't have exclusion.type set.
We just return false in this case.

This patch introduces the logic that tries to combine 2 exclusions if
possible.
We can combine 2 exclusions if
 - they are adjoining to each other and have the same exclusion type
 - the new exclusion shadows the old one.
   That's because it's not allowed to position anything in the
   shadowed area.

Example:
 <div id="SS" style="float: left; height: 10px; width: 10px"></div>
 <div id="BB" style="float: left; height: 20px; width: 20px"></div>
 +----------------+
 |SSBB
 |**BB
 We combine SS and BB exclusions including the shadowed area (**).

BUG=635619,699703
TESTS=TwoRightExclusionsShadowEachOther,
TwoLeftExclusionsShadowEachOther
==========

to

==========
Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

Note: The original patch was reviewed and submitted in
https://codereview.chromium.org/2733133002/
The only difference with the original patch is that
NGExclusion::MaybeCombineWith doesn't have NOTREACHED anymore. That's
because some tests and text exclusions don't have exclusion.type set.
We just return false in this case.

This patch introduces the logic that tries to combine 2 exclusions if
possible.
We can combine 2 exclusions if
 - they are adjoining to each other and have the same exclusion type
 - the new exclusion shadows the old one.
   That's because it's not allowed to position anything in the
   shadowed area.

Example:
 <div id="SS" style="float: left; height: 10px; width: 10px"></div>
 <div id="BB" style="float: left; height: 20px; width: 20px"></div>
 +----------------+
 |SSBB
 |**BB
 We combine SS and BB exclusions including the shadowed area (**).

BUG=635619,699703
TESTS=TwoRightExclusionsShadowEachOther,
TwoLeftExclusionsShadowEachOther

Review-Url: https://codereview.chromium.org/2743453002
Cr-Commit-Position: refs/heads/master@{#455876}
Committed:
https://chromium.googlesource.com/chromium/src/+/875a510c97b3108d5ca70c7878c9...
==========

[commit-bot: I haz the power, 2017-03-09 22:05:02]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/875a510c97b3108d5ca70c7878c9...