Roll shaderc from 4ec77979ecd7 to 6ff0205cedd3 (2 revisions)

https://chromium.googlesource.com/external/github.com/google/shaderc/+log/4ec77979ecd7..6ff0205cedd3

2020-06-10 rharrison@google.com Rolling 5 dependencies and update expectations (#1081)
2020-06-10 rharrison@google.com Remove infrastructure for and references to VS2013 (#1082)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/shaderc-chromium-autoroll
Please CC radial-bots+chrome-roll@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

Tbr: radial-bots+chrome-roll@google.com
Change-Id: Icea34093c6cd49fb0671269850e7063b1502825c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2239358
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#776978}

DEPS

@@ -301,7 +301,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'shaderc_revision': '4ec77979ecd717f88e648dea42851ee4a0385fff',
+  'shaderc_revision': '6ff0205cedd3db2e492326e3b3df7cecbfaa6629',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.