Roll src/third_party/skia/ 2b3c2a3ff..4cea3b9e9 (7 commits).

https://chromium.googlesource.com/skia.git/+log/2b3c2a3ff916..4cea3b9e9d98

$ git log 2b3c2a3ff..4cea3b9e9 --date=short --no-merges --format='%ad %ae %s'
2016-09-08 brianosman Push usage of GrColor4f into OverrideInput
2016-09-08 mtklein most is fine for *SAN bots now
2016-09-08 ethannicholas removed const from ASTVarDeclaration::fName to avoid a Chromium build failure GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2325673002
2016-09-08 mtklein Clean up target_os=llvm now that it does nothing.
2016-09-08 robertphillips Add GM/slide to simulate Android-style reveal clip
2016-09-08 halcanary Tests: DiscardableMemory test no longer relies on global state
2016-09-08 mtklein SkLiteDL: drawAsLayer()

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel
TBR=caryclark@google.com

Review-Url: https://codereview.chromium.org/2324843002
Cr-Commit-Position: refs/heads/master@{#417340}

DEPS

@@ -36,7 +36,7 @@ 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': '2b3c2a3ff9166e92ca1700e695c30ae729a3f10c',
+  'skia_revision': '4cea3b9e9d9836c926a8feb55d050993d40b4b5e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.