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Move the queueing of the swap promise from RenderWidget into
WidgetBase. This requires expose a callback AddPresentationCallback
which will be eventually be removed when LayerTreeView moves into blink.

Change-Id: I765d787bc6f1fd2246e142bc4c5a1ecc91ec79dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2090461
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#750304}