Roll src/third_party/skia/ 7f302c468..6f9f7ebb7 (1 commit).

https://skia.googlesource.com/skia.git/+log/7f302c4682f5..6f9f7ebb74f4

$ git log 7f302c468..6f9f7ebb7 --date=short --no-merges --format='%ad %ae %s'
2017-02-18 robertphillips Expand use of GrMakeCachedBitmapProxy (take 2)

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
TBR=bungeman@google.com

Review-Url: https://codereview.chromium.org/2702063002
Cr-Commit-Position: refs/heads/master@{#451495}

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': '7f302c4682f5d6eb9dc61f1fb1d12e1079024f70',
+  'skia_revision': '6f9f7ebb74f49a3b641421fd368d8101e81dd05e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.