Roll src/third_party/skia/ 9a44565e9..e6ec16356 (4 commits).

https://chromium.googlesource.com/skia.git/+log/9a44565e9946..e6ec16356ec6

$ git log 9a44565e9..e6ec16356 --date=short --no-merges --format='%ad %ae %s'
2016-08-30 mtklein Detect TSAN instead of relying on #ifdef THREAD_SANITIZER.
2016-08-30 halcanary SkPDF: hand SfntlyWrapper::SubsetFont() ttcIndex, not fontName.
2016-08-30 mtklein GN: add sksl
2016-08-30 bsalomon Remove unneeded variables from ResourceCache test GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2295883002

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

Review-Url: https://codereview.chromium.org/2291263002
Cr-Commit-Position: refs/heads/master@{#415399}

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': '9a44565e9946629c4ee776fb859d168eb953da71',
+  'skia_revision': 'e6ec16356ec677e582230002bd3ffab46fd14a49',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.