Roll src/third_party/skia/ 8f30709e9..7cad9897d (3 commits)

https://skia.googlesource.com/skia.git/+log/8f30709e93ba..7cad9897d413

$ git log 8f30709e9..7cad9897d --date=short --no-merges --format='%ad %ae %s'
2017-04-10 kjlubick Add docs for downloading prebuilt binaries from CIPD
2017-04-12 reed remove pixelref flag from google3
2017-04-11 robertphillips Disable deferred proxies for Chrome branch

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
TBR=mtklein@chromium.org

Change-Id: I68c2204e1f0ced735076b38138bade808db5bbb4
Reviewed-on: https://chromium-review.googlesource.com/475751
Reviewed-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@{#464010}

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': '8f30709e93ba377a0bf77f24aeae890d38b66e52',
+  'skia_revision': '7cad9897d413dd18adc2d95ab04d0568f788c69e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.