Roll src/third_party/skia/ e305cc1f2..56ff9a1c9 (6 commits).

https://skia.googlesource.com/skia.git/+log/e305cc1f2a44..56ff9a1c9dfd

$ git log e305cc1f2..56ff9a1c9 --date=short --no-merges --format='%ad %ae %s'
2016-12-14 kjlubick Add Galaxy Tab3 Test
2016-12-14 herb Remove tombstones from SkTHash.
2016-12-14 liyuqian Change FLAGS_analyticAA's default to true
2016-12-14 reed remove PLAIN_ENUM flag for SkClipOp
2016-12-14 bsalomon Update rect ops to use "op" in their name and return sk_sp.
2016-12-14 mtklein switch to libstdc++ for standalone Android builds.

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/2576033002
Cr-Commit-Position: refs/heads/master@{#438682}

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': 'e305cc1f2a44e47d6a0dcc0ff34e2692349aed5d',
+  'skia_revision': '56ff9a1c9dfdaf1cd6db3b62a5c2b739cd242032',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.