Bug 272455 – [GTK][WPE] Ensure that WebGL changes request a single composition

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKitGTK

[Miguel Gomez]

When there are WebGL changes, the canvas indicates that it needs to be displayed, which triggers a layerFlush:
- During this layerflush, Nicosia::GCGLANGLELayer::swapBuffersIfNeeded() is called, which pushes a new buffer into TextureMapperPlatformLayerProxy[GL|DMABuf]. In response to this, the proxy requests a composition directly to the compositor to show the new content.
- At the end of the layerFlush, a composition to show the modified content is always made.
- This causes that we have 2 compositions requested. Depending on the conditions, these two requests can be merged into a single one or trigger two different compositions, which is a waste or resources and can desync the equilibrium between the main thread and the composition.

We need to ensure that WebGL changes request a single composition.

[Miguel Gomez]

Pull request: https://github.com/WebKit/WebKit/pull/27078

[EWS]

Committed 277366@main (8ce70fa03821): <https://commits.webkit.org/277366@main>

Reviewed commits have been landed. Closing PR #27078 and removing active labels.