cc: Synchronize num copy requests to LayerImpl
With this change, precalculate meta-information no longer needs to be
run for property trees on the compositor thread. Since we don't have
a property tree-only mode yet, we can't do this in practice yet, but
it will be useful for one-off benchmarking.
Property trees currently only need two pieces of meta-information (num
unclipped descendants for building property trees on the main thread,
and num copy requests). Both of these could move to the effect tree
in the future.
R=weiliangc@chromium.org,ajuma@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/
1335383003
Cr-Commit-Position: refs/heads/master@{#350125}