Roll src/third_party/skia/ bbab477b4..c30833327 (5 commits).

https://skia.googlesource.com/skia.git/+log/bbab477b49e2..c30833327f0d

$ git log bbab477b4..c30833327 --date=short --no-merges --format='%ad %ae %s'
2016-12-12 mtklein proposed gn_to_bp fixes
2016-12-09 brianosman Make subset param to texture generation API non-optional
2016-12-09 mtklein Convert image width and height (used by tiling) to float once.
2016-12-11 update-skps Update SKP version
2016-12-12 djsollen Add documentation for being a Android RoboCop.

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
TBR=msarett@google.com

Review-Url: https://codereview.chromium.org/2572463002
Cr-Commit-Position: refs/heads/master@{#437892}

DEPS

@@ -40,7 +40,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': 'bbab477b49e2aed0f257206ce457814c953d574b',
+  'skia_revision': 'c30833327f0dda75a8fbe061f3f1966d1f6621a3',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.