1521603 - Add a helper method to check if the top level content document hasn't yet got first contentful paint and there is high prio event pending

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement)

Description

[Olli Pettay [:smaug][[e-mail]]]

Attachment: HighPriorityEventPendingForTopLevelDocumentContentfulPaint.diff

If the method returns true, we probably should yield during page load so that we get first contentful paint asap. So, it will be useful in many places and I have patches using it.

The method name is quite horrible, but hard to have descriptive name.
The high priority event could be of course for something else too, but hopefully the documentation is clear enough.

GetShell() and GetPresContext() are fast inline calls.

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Comment on attachment 9038057 [details] [diff] [review]
HighPriorityEventPendingForTopLevelDocumentContentfulPaint.diff

Review of attachment 9038057 [details] [diff] [review]:
-----------------------------------------------------------------

::: dom/base/nsContentUtils.cpp
@@ +10435,5 @@
>    return true;
>  }
>  
> +/* static */
> +bool nsContentUtils::HighPriorityEventPendingForTopLevelDocumentContentfulPaint(

Is this really ....BeforeContentfulPaint()? The current name is confusing

@@ +10438,5 @@
> +/* static */
> +bool nsContentUtils::HighPriorityEventPendingForTopLevelDocumentContentfulPaint(
> +    Document* aDocument) {
> +  if (!aDocument) {
> +    return false;

Is this an expected path? 
Since we dereference immediately, without the nullcheck it would be a clean null dereference, so an ASSERT is quite optional.

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Null check makes certain call sites simpler.

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

I'm fine with longer *BeforeContentfulPaint.
All the names are quite bad.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Attachment: HighPriorityEventPendingForTopLevelDocumentContentfulPaint.diff

HighPriorityEventPendingForTopLevelDocumentBeforeContentfulPaint
Horribly long name, but oh well.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/8ad35cea96d9
Add a helper method to check if the top level content document hasn't yet got first contentful paint and there is high prio event pending, r=jesup

Comment 6

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/8ad35cea96d9