Revert "Revert "When creating emptyp MipMap proxies, don't instantiate them immediately.""

This reverts commit 0ee866dac78b60497b4c107995d3c2747309ef8b.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Revert "When creating emptyp MipMap proxies, don't instantiate them immediately."
> 
> This reverts commit 8242c5c199f5d04e4209222b265f9e27f7c55fa7.
> 
> Reason for revert: Hitting assert on intel bots on skbug6850overlay2.skp, SkASSERT(proxy->getUniqueKey().isValid()); in processInvalidProxyUniqueKey
> 
> Original change's description:
> > When creating emptyp MipMap proxies, don't instantiate them immediately.
> > 
> > This chnages makes it match how we handle non mipped proxies where we
> > don't actually instantiate them until we need to.
> > 
> > Bug: skia:
> > Change-Id: Id0c50eefce43ef1458a3ff0bb1881a817b045279
> > Reviewed-on: https://skia-review.googlesource.com/106966
> > Commit-Queue: Greg Daniel <egdaniel@google.com>
> > Reviewed-by: Robert Phillips <robertphillips@google.com>
> 
> TBR=egdaniel@google.com,robertphillips@google.com
> 
> Change-Id: I1fa6165b69c5bbb1d6bb10abba33dcdb55a27ba3
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:
> Reviewed-on: https://skia-review.googlesource.com/107263
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Greg Daniel <egdaniel@google.com>

TBR=egdaniel@google.com,robertphillips@google.com

Bug: skia:
Change-Id: Ice34283f9ac183faed6e061d8162cf2226b18289
Reviewed-on: https://skia-review.googlesource.com/107320
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
9 files changed