Roll src/third_party/skia/ 2f6878778..766f9cd55 (1 commit)

https://skia.googlesource.com/skia.git/+log/2f687877835b..766f9cd5553a

$ git log 2f6878778..766f9cd55 --date=short --no-merges --format='%ad %ae %s'
2017-05-19 mtklein dither copies when decreasing precision

Created with:
  roll-dep src/third_party/skia
BUG=720105


Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls


CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=egdaniel@chromium.org

Change-Id: I3cf00fe5b9cb0e8923d88166bbe89600cf360931
Reviewed-on: https://chromium-review.googlesource.com/509942Reviewed-by: Skia Deps Roller <skia-deps-roller@chromium.org>
Commit-Queue: Skia Deps Roller <skia-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#473443}

DEPS

@@ -40,7 +40,7 @@ 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': '2f687877835b60497a48537b940cd634088eedf4',
+  'skia_revision': '766f9cd5553ab091b85d287a79f47cbb91ad7989',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.