This CL makes it possible for pulled-forward-layers to be atlased. It currently has a couple glaring limitations (which is why it is disabled):
1) the atlased layers cannot be purged nor aged out
2) the texture backing the atlas is not pulled from (or returned to) the resource cache
#1 is on hold until we have a recycling rectanizer
A separate major limitation (the non-atlased layers aren't cached) is blocked until we can transmute entries in the resource cache from scratch to non-scratch while potentially preserving their contents.
R=bsalomon@google.com
Author: robertphillips@google.com
Review URL: https://codereview.chromium.org/354533004
55e61f0ef4