Lots of layers get solid color but transparent contents layers now

[Simon Fraser (smfr)]

After making layers with contents layers have pink borders, we can see from http://www.webkit.org/blog-files/3d-transforms/poster-circle.html that we're making color contents layers for lots of things now, but setting a transparent color on them.

RenderLayerBacking::updateDirectlyCompositedBackgroundColor() is getting rendererBackgroundColor(), which returns a valid (but transparent) color.

[Noam Rosenthal]

At least for TextureMapper this is not a problem, I'm not familiar with the implications of this for CA.

[Simon Fraser (smfr)]

Do you avoid contentsLayers for the transparent color?

[Noam Rosenthal]

Content layers are really more of a CA concept... In TextureMapper we just mark those layers as having a solid color and no backing store and they're rendered that way.
But in general it should be safe to treat "transparent" solid color as a sign to delete the content layer, as an optimization inside GraphicsLayerCA and friends.

[Simon Fraser (smfr)]

Created attachment 216343 [details]
Patch

[Tim Horton]

Comment on attachment 216343 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=216343&action=review

> Source/WebCore/ChangeLog:13
> +        Fix only making a background-color layer if the color is not transparent (zero alpha).

fix only making.

[Simon Fraser (smfr)]

https://trac.webkit.org/r158889