Fix position of composited, paginated inlines.

Fix position of composited, paginated inlines.

Previously, we were not including the offset from the PaintLayer of the composited layer when calling PaintLayer::visualOffsetFromAncestor to compute GraphicsLayer
offset from the composited ancestor.

It's important to include this offset when converting from logical to visual
coordinates across a paginated layer boundary, because the offset influences the
fragment offset of the composited layer.

BUG=667213
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2738943004
Cr-Commit-Position: refs/heads/master@{#455982}
Committed: https://chromium.googlesource.com/chromium/src/+/a1277dcaaae26865cc6591bda0d6d696b5a0f073

[chrishtr, 2017-03-08 22:35:56]

Description was changed from

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BUG=
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to

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none

BUG=
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2017-03-08 22:38:32]

Description was changed from

==========
none


none


none

BUG=
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Fix position of composited, paginated inlines.

Previously, we were not including the offset from the PaintLayer of the
composited layer when calling PaintLayer::visualOffsetFromAncestor to compute
GraphicsLayer
offset from the composited ancestor.

It's important to include this offset when converting from logical to visual
coordinates across a paginated layer boundary, because the offset influences the
fragment offset of the composited layer.

BUG=667213
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2017-03-08 22:40:06]

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

[commit-bot: I haz the power, 2017-03-08 22:40:31]

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, 2017-03-08 23:36:07]

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

[commit-bot: I haz the power, 2017-03-08 23:36:08]

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

[chrishtr, 2017-03-09 01:18:31]

chrishtr@chromium.org changed reviewers:
+ trchen@chromium.org

[trchen, 2017-03-09 23:41:16]

After a lengthy offline discussion, we discovered that this CL will also change
behavior for composited fragmented descendants with negative visual overflow.
Either behavior sounds equally good(or bad) because composited visual
fragmentation was never supported, but this definitely is a better heuristics
for inline elements.

So lgtm except some suggestion about comments. (For the point of view as a
first-time reader, I feel the revised comment gives more context.)

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
(right):

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:809:
const LayoutPoint offsetFromPaintLayer) {
const LayoutPoint localRepresentativePointForFragmentation) {

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:814:
// fragmentation offset if compositedAncestor crosses a pagination boundary.
// Currently visual fragmentation for composited layers is not implemented,
// For fragmented contents, we paint in logical coordinate of the flow thread,
// then split the result by fragment boundary and paste each part into each
// fragment's physical position.
// Since composited layers don't support visual fragmentation, we have to
// choose a "representative" fragment to position the painted contents. This
// is where localRepresentativePointForFragmentation comes into play.
// The fragment that the representative point resides in will be chosen as
// the representative fragment for layer position purpose.
// For layers that are not fragmented, the point doesn't affect behavior as
// there is one and only one fragment.

[chrishtr, 2017-03-10 01:50:03]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2017-03-10 01:50:04]

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
(right):

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:809:
const LayoutPoint offsetFromPaintLayer) {
On 2017/03/09 at 23:41:16, trchen wrote:
> const LayoutPoint localRepresentativePointForFragmentation) {

Done.

https://codereview.chromium.org/2738943004/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:814:
// fragmentation offset if compositedAncestor crosses a pagination boundary.
On 2017/03/09 at 23:41:16, trchen wrote:
> // Currently visual fragmentation for composited layers is not implemented,
> // For fragmented contents, we paint in logical coordinate of the flow thread,
> // then split the result by fragment boundary and paste each part into each
> // fragment's physical position.
> // Since composited layers don't support visual fragmentation, we have to
> // choose a "representative" fragment to position the painted contents. This
> // is where localRepresentativePointForFragmentation comes into play.
> // The fragment that the representative point resides in will be chosen as
> // the representative fragment for layer position purpose.
> // For layers that are not fragmented, the point doesn't affect behavior as
> // there is one and only one fragment.

Done.

[chrishtr, 2017-03-10 01:50:04]

The patchset sent to the CQ was uploaded after l-g-t-m from trchen@chromium.org
Link to the patchset: https://codereview.chromium.org/2738943004/#ps60001
(title: "none")

[commit-bot: I haz the power, 2017-03-10 01:50:22]

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, 2017-03-10 03:55:57]

CQ is committing da patch.

Bot data: {"patchset_id": 60001, "attempt_start_ts": 1489110603902760,
"parent_rev": "a958e2950a29ba6f293d95e3a93c3c0235db2b94", "commit_rev":
"a1277dcaaae26865cc6591bda0d6d696b5a0f073"}

[commit-bot: I haz the power, 2017-03-10 03:56:48]

Description was changed from

==========
Fix position of composited, paginated inlines.

Previously, we were not including the offset from the PaintLayer of the
composited layer when calling PaintLayer::visualOffsetFromAncestor to compute
GraphicsLayer
offset from the composited ancestor.

It's important to include this offset when converting from logical to visual
coordinates across a paginated layer boundary, because the offset influences the
fragment offset of the composited layer.

BUG=667213
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Fix position of composited, paginated inlines.

Previously, we were not including the offset from the PaintLayer of the
composited layer when calling PaintLayer::visualOffsetFromAncestor to compute
GraphicsLayer
offset from the composited ancestor.

It's important to include this offset when converting from logical to visual
coordinates across a paginated layer boundary, because the offset influences the
fragment offset of the composited layer.

BUG=667213
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2738943004
Cr-Commit-Position: refs/heads/master@{#455982}
Committed:
https://chromium.googlesource.com/chromium/src/+/a1277dcaaae26865cc6591bda0d6...
==========

[commit-bot: I haz the power, 2017-03-10 03:56:49]

Committed patchset #4 (id:60001) as
https://chromium.googlesource.com/chromium/src/+/a1277dcaaae26865cc6591bda0d6...