Raster into an SkPicture before rendering a DisplayList.

Raster into an SkPicture before rendering a DisplayList.

Rasterizing a display list is more than 2x slower than rasterizing
in the existing architecture. This is due to recording more with a
display list and we have no bounding hierarchy to cull content quickly.

We can address this by creating an SkPicture from the list, with a bounding
hierarchy, and rasterizing that instead. The result is slightly faster than
the non-S.P. pipeline but uses 2x more memory.

Identical patch to https://codereview.chromium.org/966443003/. Committing
TBR thanks to previous LGTM for exact same patch. Expectations have been
updated.

TBR=chrishtr,ajuma
BUG=464738

Review URL: https://codereview.chromium.org/1004753002

Cr-Commit-Position: refs/heads/master@{#320317}