Roll src/third_party/skia/ e12c69e78..9d687dfa3 (5 commits)

https://skia.googlesource.com/skia.git/+log/e12c69e78db3..9d687dfa3e34

$ git log e12c69e78..9d687dfa3 --date=short --no-merges --format='%ad %ae %s'
2017-05-05 msarett Avoid interpolating color lut with less than 2 points
2017-04-25 halcanary SkDiscardableMemoryPool: always have a mutex for testing
2017-05-05 egdaniel Split tracking of TexelBuffers from normal samplers
2017-05-05 csmartdalton GL: track enabled vertex arrays as a count rather than a mask
2017-05-05 ethannicholas sksl optimizer fixes

Created with:
  roll-dep src/third_party/skia


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
[email protected]

Change-Id: Ia1ab0841fbe43a42615589d46a1c7cd27f4e32f2
Reviewed-on: https://chromium-review.googlesource.com/497608
Reviewed-by: Skia Deps Roller <[email protected]>
Commit-Queue: Skia Deps Roller <[email protected]>
Cr-Commit-Position: refs/heads/master@{#469695}

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': 'e12c69e78db3b6451c42e36524ae9e87f75f24fc',
+  'skia_revision': '9d687dfa3e341bc4bae7806b6e3262ae3d441889',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.