Compositor recovery recreated contexts and replayed viewport sizes,
but it left the restarted helper with the default display metadata. A
recovered context could fall back to a 60 Hz timer instead of the
window's current display id and refresh rate until the frontend later
observed a screen change.
Store the display id in the shared view state, alongside the existing
maximum frame rate, and replay both values while restoring view state
after reconnect.
The browser process forwards the maximum frame rate to WebContent, but
the compositor process had no copy of that display timing metadata or
the display identity needed by compositor-local vsync.
Add one compositor control IPC message carrying the optional display ID
and refresh rate together, and store both values on each compositor
context.
Seed the page background fallback from the platform color scheme before
WebContent has painted. Update the same fallback when the platform theme
changes, and when the preferred color scheme is forced through the debug
menu, so unpainted web view areas use the matching Canvas color.
Generalize the backing store sharing abstraction into SharedImage, which
represents shared GPU memory independently of Skia and can be used to
share memory between different processes or different GPU contexts.
The set_viewport_size and set_device_pixel_ratio IPC messages were sent
separately, potentially causing a race condition when the DPR changes
(e.g. moving a window between screens): the DPR message would arrive
and use a stale viewport size, computing a temporarily wrong CSS
viewport. Combine both into a single set_viewport IPC that updates the
device viewport size and DPR together.
Instead of copying the Bitmap that wraps the IOSurface, we can just
present the IOSurface directly. This significantly reduces CPU usage in
the UI process, particularly at high refresh rates such as 120Hz where
it would saturate a full CPU core.
This is done by using CAMetalLayer and blitting the IOSurface to the
next drawable buffer, which handles triple buffering, locking the
IOSurface and vsync automatically. This also allows the Metal HUD to
work, but the only accurate stat is the frame intervals/FPS because
it's in the UI layer, not WebContent. However, that's still useful
to detect frame drops.
This removes the old autoplay allowlist file in favor of the new site
setting. We still support the command-line flag to enable autoplay
globally, as this is needed for WPT.
LibWebView now knows how to launch RequestServer and ImageDecoderServer
without help from the UI, so let's move ownership of these services over
to LibWebView for de-duplication.
We will want to re-inform WebContent of the system visibility state when
we create a new process after a crash. This changes the IPC to just send
the enum value directly, instead of a boolean, so that we can just store
that enum value directly on the ViewImplementation class.
