Change pdf compositor interface to "compositor"

Use noun instead of verb for the interface name to be consistent with
other interface names. Thus change the name from "composite" to
"compositor".

BUG=455764

Change-Id: Ib3ebd6d5775181dd4a96c0c79ff3a82a56692952
Reviewed-on: https://chromium-review.googlesource.com/650533
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Wei Li <weili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#499747}
3 files changed