ui: Remove thread/lock check in test context provider

This is not something that any of the other context providers do inside
of ContextSupport().  This is to support this patch:

https://chromium-review.googlesource.com/c/chromium/src/+/998682
...which adds calls to IsResourceReadyToDraw which previously never
happened in the browser (because TileManager only issued them when
in smoothness mode, which is never true for the browser.

Landing separately in case the other patch gets reverted.

Change-Id: I939db78c76b0d613824c04f52d8098226cba59a2
Reviewed-on: https://chromium-review.googlesource.com/1003755
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549390}
1 file changed