Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/5a28ce539ba64f44324c9ce311b91ffc851d6ffd
Cr-Commit-Position: refs/heads/master@{#417002}

[Stephen Chennney, 2016-09-07 15:52:26]

The previous attempt at this was reverted due to Win 7 Test bot failing the
DCHECK(!m_stackingNode->zOrderListsDirty()) in the
PopupBlockerBrowserTest.AllowPopupThroughContentSetting test. The failure does
not repro on Linux so my guess is that Win 7 is slower and that is causing
issues.

I added a TODO to look into the problem and reverted back to an if statement
checking the zOrderListsDirty status.

[chrishtr, 2016-09-07 16:45:41]

I don't see any DCHECKs removed in this patch. ?

[Stephen Chennney, 2016-09-07 16:51:37]

On 2016/09/07 16:45:41, chrishtr wrote:
> I don't see any DCHECKs removed in this patch. ?

Because this is against the original code, not the version with the DCHECK that
was reverted. I'll clean up the change description.

[Stephen Chennney, 2016-09-07 16:52:10]

Description was changed from

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) with the DCHECK removed.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that
patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2016-09-07 16:57:43]

lgtm

[Stephen Chennney, 2016-09-07 16:58:24]

The CQ bit was checked by schenney@chromium.org

[commit-bot: I haz the power, 2016-09-07 16:58:53]

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, 2016-09-07 18:27:57]

Description was changed from

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that
patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that
patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[commit-bot: I haz the power, 2016-09-07 18:27:58]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-07 18:29:48]

Description was changed from

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that
patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

The PaintLayer::backgroundIsKnownToBeOpaque method is currently
only called by GraphicsLayers on their owning paint layer, or
by the recursive child call. The former is by definition
always called on a self painting layer, while the latter
already has a test to prevent consideration of layers that
do not paint into the backing in question. Hence we can
remove the check for self painting layer status.

These checks cause chicken-and-egg problems when the method
is called by the layer itself in order to identify compositing
reasons. In such cases we are not concerned with self layer
status; we are in fact trying to determine that status.

This is a relanding of issue 2297873002 at patchset 140001
(http://crrev.com/2297873002#ps140001) without the DCHECK that was in the that
patch.

R=chrishtr@chromium.org
BUG=381840
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/5a28ce539ba64f44324c9ce311b91ffc851d6ffd
Cr-Commit-Position: refs/heads/master@{#417002}
==========

[commit-bot: I haz the power, 2016-09-07 18:29:49]

Patchset 1 (id:??) landed as
https://crrev.com/5a28ce539ba64f44324c9ce311b91ffc851d6ffd
Cr-Commit-Position: refs/heads/master@{#417002}