Add always-threaded SkRecord quilt tests.

Add always-threaded SkRecord quilt tests.

Now that we're drawing tiles threaded like implside painting, remove the checks
that those lock counts are balanced.  They're just not right for anyone anymore.

SkBitmaps themselves are not threadsafe (even const ones), so shallow copy them
on playback of an SkRecord.  (The underlying SkPixelRefs are threadsafe.)

Simplify quilt drawing by using SkBitmap::extractSubset.  No need for locking.

Bump up to 256x256 tiles.  16x16 tiles just murders performance (way too much
contention).  This has the nice side effect of letting us enable a bunch more
GMs for quilt mode; they drew wrong with small tiles but exactly right with large.

BUG=171776
Committed: https://skia.googlesource.com/skia/+/7cdc1ee11545a10708e857adf1d4a94a2f1e2a48

[reed1, 2014-07-07 17:22:48]

lgtm

[mtklein, 2014-07-07 17:23:25]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-07-07 17:24:15]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/371023005/100001

[commit-bot: I haz the power, 2014-07-07 17:41:09]

Change committed as 7cdc1ee11545a10708e857adf1d4a94a2f1e2a48