UpdateServiceTest pass now that 844973 is fixed

TBR=jam@chromium.org

Bug: 844973
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: I2fa684a39ddb01c582173d6955fa264792c779ea
Reviewed-on: https://chromium-review.googlesource.com/1136718
Commit-Queue: Doug Turner <dougt@chromium.org>
Reviewed-by: Doug Turner <dougt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574996}

testing/buildbot/filters/mojo.fyi.network_browser_tests.filter

@@ -71,12 +71,9 @@
 -ProfileWithoutMediaCacheBrowserTest.NoSeparateMediaCache
 
 # components/update_client/ still uses URLFetcher.
-# https://crbug.com/844973
--UpdateServiceTest.NoUpdate
+# After bug 844973 was fixed, these two still fail/crash:
 -UpdateServiceTest.PolicyCorrupted
 -UpdateServiceTest.SuccessfulUpdate
--UpdateServiceTest.TwoUpdateCheckErrors
--UpdateServiceTest.UpdateCheckError
 
 # about:net-internals should be largely removed before shipping the network
 # service.