Fix the compositing of placeholder canvas backgrounds

Fix the compositing of placeholder canvas backgrounds

In CompositedLayerMapping::updateContentsOpaque(), we were falsely
assuming that an opaque CSS background made the content layer opaque
this was causing rendering artifacts because culling optimizations
were kicking in when they should not.

BUG=703673
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2774903003
Cr-Commit-Position: refs/heads/master@{#459583}
Committed: https://chromium.googlesource.com/chromium/src/+/9e0bad82923e80164de225930fefe0986c1aa98d

[Justin Novosad, 2017-03-24 18:55:50]

Description was changed from

==========
Fix the compositing of placeholder canvas backgrounds

In CompositedLayerMapping::updateContentsOpaque(), we were falsely
assuming that an opaque CSS background made the content layer opaque
this was causing rendering artifacts because culling optimizations
were kicking in when they should not.

BUG=703673
==========

to

==========
Fix the compositing of placeholder canvas backgrounds

In CompositedLayerMapping::updateContentsOpaque(), we were falsely
assuming that an opaque CSS background made the content layer opaque
this was causing rendering artifacts because culling optimizations
were kicking in when they should not.

BUG=703673
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[Justin Novosad, 2017-03-24 18:56:46]

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

[commit-bot: I haz the power, 2017-03-24 18:57:25]

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

[Justin Novosad, 2017-03-24 19:03:57]

junov@chromium.org changed reviewers:
+ xlai@chromium.org

[Justin Novosad, 2017-03-24 19:03:57]

PTAL.

The changes to CompositedLayerMapping is the actual fix.  The changes to
OffscreenCanvasFrameDispatcherImpl, are drive-by tweaks to correct unreliable
information that was being passed to CompositorFrame, which could lead to
similar bugs in the future if the ui compositor started doing culling
optimizations.

[xlai (Olivia), 2017-03-24 20:24:59]

https://codereview.chromium.org/2774903003/diff/20001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
(right):

https://codereview.chromium.org/2774903003/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:122:
static inline bool isPlaceholderCanvas(const LayoutObject& layoutObject) {
You don't need to add this function. There is "isCanvasControlledByOffscreen"
function that's exactly same as this.

[Justin Novosad, 2017-03-24 20:43:50]

On 2017/03/24 20:24:59, xlai (Olivia) wrote:
>
https://codereview.chromium.org/2774903003/diff/20001/third_party/WebKit/Sour...
> File
> third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
> (right):
> 
>
https://codereview.chromium.org/2774903003/diff/20001/third_party/WebKit/Sour...
>
third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp:122:
> static inline bool isPlaceholderCanvas(const LayoutObject& layoutObject) {
> You don't need to add this function. There is "isCanvasControlledByOffscreen"
> function that's exactly same as this.

LOL thx.

[Justin Novosad, 2017-03-24 20:54:35]

Done.  I kept the new version of the function ;-)

[xlai (Olivia), 2017-03-24 21:09:44]

The CQ bit was checked by xlai@chromium.org

[xlai (Olivia), 2017-03-24 21:09:45]

lgtm

[commit-bot: I haz the power, 2017-03-24 21:10:32]

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, 2017-03-24 22:44:44]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1490389784630830,
"parent_rev": "0c5ada71f25ba9b76a635f4be3cbd08ac0b007ce", "commit_rev":
"9e0bad82923e80164de225930fefe0986c1aa98d"}

[commit-bot: I haz the power, 2017-03-24 22:45:32]

Description was changed from

==========
Fix the compositing of placeholder canvas backgrounds

In CompositedLayerMapping::updateContentsOpaque(), we were falsely
assuming that an opaque CSS background made the content layer opaque
this was causing rendering artifacts because culling optimizations
were kicking in when they should not.

BUG=703673
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Fix the compositing of placeholder canvas backgrounds

In CompositedLayerMapping::updateContentsOpaque(), we were falsely
assuming that an opaque CSS background made the content layer opaque
this was causing rendering artifacts because culling optimizations
were kicking in when they should not.

BUG=703673
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2774903003
Cr-Commit-Position: refs/heads/master@{#459583}
Committed:
https://chromium.googlesource.com/chromium/src/+/9e0bad82923e80164de225930fef...
==========

[commit-bot: I haz the power, 2017-03-24 22:45:33]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/9e0bad82923e80164de225930fef...