commit 395848a6a71b1332ac01dad42af61b457b7afe87
author Jean-Philippe Gravel <jpgravel@chromium.org> Tue Apr 01 20:14:36 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Apr 01 20:14:36 2025
tree d26d51f25eb1db7cc323a71a59a0ff2d0ef98aa8
parent 3be54c4356991340d9672ea0712602ac4834b0d0

Add a guard to enable context restoration

HTMLCanvasElement disables calls to GetOrCreateResourceProvider while
the context is lost, to ensure that the context isn't restored
out-of-line by mistake. Restoration must happen in
TryRestoreContextEvent, which takes care of dispatching the
oncontextrestored event to the web page if restoration succeeds. If the
restoration happens my a unexpected call to GetOrCreateCRP, the event
would not be dispatched.

This however causes complication in the restore process, because to
restore the context, we need to call GetOrCreateCRP, which is disabled
by context loss. This is not a problem in Restore() because we call the
internal impl version of GetOrCreateCRP.
CanCreateCanvas2dResourceProvider on the other hand has a code path
that will fail while the context is lost. For synthetic context loss, we
call GetOrCreateResourceProviderWithCurrentRasterModeHint, which only
works because right now because synthetic context losses do not set
CanvasResourceHost::context_lost_. This will change in a follow up CL
though, when we merge context_lost_ and context_lost_mode_.

This CL addresses these issues by adding a stack-bound guard which
enables GetOrCreateCRP for the lifetime of TryRestoreContextEvent.

Bug: 404257881
Change-Id: Ib78a44517c769b0619929799d8cd5a3ac736f5e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6386730
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Jean-Philippe Gravel <jpgravel@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1441137}