GitLab

Add some DCHECK-only code to validate that a CompositorFrame is always
submitted only between calls to WillBeginImplFrame() and
DidFinishImplFrame() (i.e. when a valid BeginFrameArgs is being tracked
by the LayerTreeHostImpl).

Change-Id: I9f344135163d8fabf15c7b670a4a80eb25079e18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894912
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713722}