Roll src/third_party/skia/ e7904f397..b6318bf44 (3 commits).

https://chromium.googlesource.com/skia.git/+log/e7904f3979e2..b6318bf44dd8

$ git log e7904f397..b6318bf44 --date=short --no-merges --format='%ad %ae %s'
2016-09-16 herb Compile the skia library for windows using gn.
2016-09-16 halcanary Revert of SkPDF:  Implement /ActualText to make text extraction correct. (patchset #11 id:220001 of https://codereview.chromium.org/2322403002/ )
2016-09-16 bungeman Sane use of FcPatternGetXXX in SkFontConfigInterface.

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

Review-Url: https://codereview.chromium.org/2347103004
Cr-Commit-Position: refs/heads/master@{#419288}

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': 'e7904f3979e2e8b80b5d77165291e649ff1278dd',
+  'skia_revision': 'b6318bf44dd89dc8465dcf48ba820701eae24acb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.