This CL adds a feature to allow decoupling BeginImplFrame() from
BeginMainFrame(). It works by not sending a BeginMainFrame() (but not
marking it as sent either) in the scheduler, on high refresh rate
clients.
Concretely, when the feature is enabled, no more than one BeginMainFrame
is sent per 1/60th of a second, which in practice means that impl-side
scrolling (even when blocked on main, i.e. with a non-passive observer)
and CSS animations work at 120fps, but main updates
(i.e. requestAnimationFrame()) happen at 60fps.
This patch works, but is not 100% complete, hence the feature is
disabled, though exercized with unit tests.
Change-Id: Iab0b0aad76ee4437b4ed7a39137fd88b1b5b8a7e
Bug: 379678455
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6054335
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1395984}
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