Previously we allowed copies to a sized format only if the depth of each
component matched (including 0 depth). Now we require that the bit depth of
non-empty component matches.

BUG=605775

Change-Id: If8abab886b0da5a1c8e89adabf3809f928dcedce
Reviewed-on: https://chromium-review.googlesource.com/340382Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>