Roll src/third_party/skia/ bbb6dc80f..1c971faab (1 commit).

https://chromium.googlesource.com/skia.git/+log/bbb6dc80fdfe..1c971faab7b2

$ git log bbb6dc80f..1c971faab --date=short --no-merges --format='%ad %ae %s'
2016-01-27 mtklein SkPngFilters: use normal pointer types.

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

Review URL: https://codereview.chromium.org/1641953002

Cr-Commit-Position: refs/heads/master@{#371961}

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': 'bbb6dc80fdfe6ff08cc1abb1a401bd958ced9602',
+  'skia_revision': '1c971faab7b201dfcd71b2d684c79b6aa5c2fafd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.