Don't always invalidate collapsed borders during table layout

Don't always invalidate collapsed borders during table layout

Many layout changes e.g. resizing doesn't affect computed collapsed
borders so don't need to invalidate collapsed borders.

We need to invalidate collapsed borders when
1. Table sections are set need recalc (when table structure changes);
2. A cell is appended into a row (which could belong to 1 but we have an
   optimization not to recalc table sections if the added cell is the
   last cell of the table);
3. Border style changes;
4. border-collapse CSS property changes;

This CL will reduce frame time of PerformanceTests/Mutation/large-
table-row-height-change-with-collapsed-border.html (in
https://codereview.chromium.org/2842313002/) by about 35% by avoiding
unnecessary collapsed border recalculations.

BUG=626748
Review-Url: https://codereview.chromium.org/2840723005
Cr-Commit-Position: refs/heads/master@{#467694}
Committed: https://chromium.googlesource.com/chromium/src/+/bb2388b6cee45ca8cba764245b2886727b3fafb8

[Xianzhu, 2017-04-26 19:32:13]

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

[commit-bot: I haz the power, 2017-04-26 19:33:45]

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, 2017-04-26 21:21:19]

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

[commit-bot: I haz the power, 2017-04-26 21:21:20]

Dry run: This issue passed the CQ dry run.

[Xianzhu, 2017-04-26 21:45:22]

Description was changed from

==========
Don't always invalidate collapsed borders during table layout

Many layout changes e.g. resizing doesn't affect computed collapsed
borders so don't need to invalidate collapsed borders.

We need to invalidate collapsed borders when
1. Table sections are set need recalc (when table structure changes);
2. A cell is appended into a row (which could belong to 1 but we have an
   optimization not to recalc table sections if the added cell is the
   last cell of the table);
3. Border style changes;
4. border-collapse CSS property changes;

BUG=626748
==========

to

==========
Don't always invalidate collapsed borders during table layout

Many layout changes e.g. resizing doesn't affect computed collapsed
borders so don't need to invalidate collapsed borders.

We need to invalidate collapsed borders when
1. Table sections are set need recalc (when table structure changes);
2. A cell is appended into a row (which could belong to 1 but we have an
   optimization not to recalc table sections if the added cell is the
   last cell of the table);
3. Border style changes;
4. border-collapse CSS property changes;

This CL will reduce frame time of PerformanceTests/Mutation/large-
table-row-height-change-with-collapsed-border.html (in
https://codereview.chromium.org/2842313002/) by about 35% by avoiding
unnecessary collapsed border recalculations.

BUG=626748
==========

[Xianzhu, 2017-04-26 21:45:34]

wangxianzhu@chromium.org changed reviewers:
+ pdr@chromium.org, wkorman@chromium.org

[wkorman, 2017-04-26 23:57:35]

lgtm

https://codereview.chromium.org/2840723005/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/LayoutTableRow.cpp (right):

https://codereview.chromium.org/2840723005/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/LayoutTableRow.cpp:175:
enclosing_table->InvalidateCollapsedBorders();
Would we consider further optimizing this case? We invalidate the whole table
but we may only need to actually invalidate a portion of it.

Asking because, if the answer is perhaps down the line, then we should add a
TODO comment. If not, no worries.

[Xianzhu, 2017-04-27 15:43:40]

https://codereview.chromium.org/2840723005/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/layout/LayoutTableRow.cpp (right):

https://codereview.chromium.org/2840723005/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/layout/LayoutTableRow.cpp:175:
enclosing_table->InvalidateCollapsedBorders();
On 2017/04/26 23:57:35, wkorman wrote:
> Would we consider further optimizing this case? We invalidate the whole table
> but we may only need to actually invalidate a portion of it.
> 
> Asking because, if the answer is perhaps down the line, then we should add a
> TODO comment. If not, no worries.

This marks the table's collapsed borders data structure dirty, and later we'll
update it. In next steps (https://codereview.chromium.org/2805103003/), update
of collapsed borders will be incremental with invalidation flag per cell, but
here we still need to invalidate the table collapsed borders here.

[Xianzhu, 2017-04-27 15:43:44]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2017-04-27 15:44:19]

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, 2017-04-27 15:51:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493307824187170, "parent_rev":
"e79777a2947a3887983485354e03c756970c7241", "commit_rev":
"bb2388b6cee45ca8cba764245b2886727b3fafb8"}

[commit-bot: I haz the power, 2017-04-27 15:52:08]

Description was changed from

==========
Don't always invalidate collapsed borders during table layout

Many layout changes e.g. resizing doesn't affect computed collapsed
borders so don't need to invalidate collapsed borders.

We need to invalidate collapsed borders when
1. Table sections are set need recalc (when table structure changes);
2. A cell is appended into a row (which could belong to 1 but we have an
   optimization not to recalc table sections if the added cell is the
   last cell of the table);
3. Border style changes;
4. border-collapse CSS property changes;

This CL will reduce frame time of PerformanceTests/Mutation/large-
table-row-height-change-with-collapsed-border.html (in
https://codereview.chromium.org/2842313002/) by about 35% by avoiding
unnecessary collapsed border recalculations.

BUG=626748
==========

to

==========
Don't always invalidate collapsed borders during table layout

Many layout changes e.g. resizing doesn't affect computed collapsed
borders so don't need to invalidate collapsed borders.

We need to invalidate collapsed borders when
1. Table sections are set need recalc (when table structure changes);
2. A cell is appended into a row (which could belong to 1 but we have an
   optimization not to recalc table sections if the added cell is the
   last cell of the table);
3. Border style changes;
4. border-collapse CSS property changes;

This CL will reduce frame time of PerformanceTests/Mutation/large-
table-row-height-change-with-collapsed-border.html (in
https://codereview.chromium.org/2842313002/) by about 35% by avoiding
unnecessary collapsed border recalculations.

BUG=626748

Review-Url: https://codereview.chromium.org/2840723005
Cr-Commit-Position: refs/heads/master@{#467694}
Committed:
https://chromium.googlesource.com/chromium/src/+/bb2388b6cee45ca8cba764245b28...
==========

[commit-bot: I haz the power, 2017-04-27 15:52:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/bb2388b6cee45ca8cba764245b28...