Roll src/third_party/skia/ 774831a4e..f1b438242 (2 commits)

https://skia.googlesource.com/skia.git/+log/774831a4e80f..f1b4382421f2

$ git log 774831a4e..f1b438242 --date=short --no-merges --format='%ad %ae %s'
2017-04-20 brianosman Rename SkImage_Generator to SkImage_Lazy
2017-04-20 egdaniel Revert "Revert "Plumb GrBackendTexture throughout skia.""

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=reed@chromium.org

Change-Id: I9c8b5d59ad65bc41ffa20e2d19b49384e7988170
Reviewed-on: https://chromium-review.googlesource.com/483074
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@{#466108}

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': '774831a4e80f49cfec3cb78f684bd44cb19a7b2a',
+  'skia_revision': 'f1b4382421f24563f1df07942a98a234220e687e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.