Roll src/third_party/skia/ c161310ff..830dfd87a (11 commits).

https://chromium.googlesource.com/skia.git/+log/c161310ffdbb..830dfd87a770

$ git log c161310ff..830dfd87a --date=short --no-merges --format='%ad %ae %s'
2016-03-16 reed add blitprocs to shaders
2016-03-16 cjacek Minor mingw cross compilation fix.
2016-03-16 robertphillips Revert of Add SkSpecialImage::extractSubset & NewFromPixmap (patchset #5 id:80001 of https://codereview.chromium.org/1787883002/ )
2016-03-16 mtklein Use std::unique_ptr.
2016-03-16 senorblanco GrTessellator: don't reuse the previous vertex buffer on a cache miss.
2016-03-16 halcanary Doc: pdf illustration
2016-03-16 mtklein Revert of Use std::unique_ptr. (patchset #10 id:170001 of https://codereview.chromium.org/1780933003/ )
2016-03-16 robertphillips Add SkSpecialImage::extractSubset & NewFromPixmap
2016-03-16 djsollen Cleanup download scripts related to new Android NDK. GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1810603002
2016-03-16 mtklein Use std::unique_ptr.
2016-03-16 mtklein Split uninteresting hash lines correctly on Windows.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=bungeman@google.com

Review URL: https://codereview.chromium.org/1808663003

Cr-Commit-Position: refs/heads/master@{#381545}

DEPS

@@ -39,7 +39,7 @@ 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': 'c161310ffdbbcb3b023da2e375faefd211fa52e8',
+  'skia_revision': '830dfd87a7707f687e13da5be645e75c746a2cf5',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.