Restore bitmap dedup in SkPictureRecord.  Cuts RAM usage of DM by half.

This should fix our failing 32-bit test bots.

BUG=skia:

Review URL: https://codereview.chromium.org/715423003
start to replace onCreateDevice with onCreateCompatibleDevice

the new virtual takes a struct which we can amend in the future w/o having to
update our subclasses in chrome.

BUG=skia:
NOTRY=True

Review URL: https://codereview.chromium.org/723743002