Re-enable SRC_ClearKey/EncryptedMediaTest.FrameSizeChangeVideo/0 with network service.

This was disabled in August 2017, and since that time URLLoader got better error handling in the referenced method.

Change-Id: I9a6192891d67a509edfdb3c47c362b77140fe84b
Reviewed-on: https://chromium-review.googlesource.com/c/1395537Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619861}

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

@@ -2,11 +2,6 @@
 # feature X that is already not working), please add it beside the existing
 # failures. Otherwise please reach out to network-service-dev@.
 
-# services/network/url_loader.cc should handle failure in
-# URLLoaderImpl::OnResponseBodyStreamRead(). Note this is flaky, so it will pass
-# sometimes.
--SRC_ClearKey/EncryptedMediaTest.FrameSizeChangeVideo/0
-
 # https://crbug.com/846352: CORB/NetworkService: Remove
 # CrossSiteDocumentResourceHandler while preserving test coverage - the tests
 # below can be probably removed altogether once NetworkService ships and the