Update webview network service filter with new failing test

This should fix the Android Mojo bot failing. The asserts in this test
were changed in http://crrev.com/c/1338660.

TBR=timvolodine@chromium.org

Bug: 893580
Change-Id: I9ce72b7726e553758f80b379c0c652df72b5909d
Reviewed-on: https://chromium-review.googlesource.com/c/1354441Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611929}

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

@@ -121,6 +121,7 @@
 -org.chromium.android_webview.test.LoadDataWithBaseUrlTest.testLoadDataWithBaseUrlAccessingFile
 -org.chromium.android_webview.test.LoadDataWithBaseUrlTest.testSetCookieInIframe
 -org.chromium.android_webview.test.LoadDataWithBaseUrlTest.testThirdPartyCookieInIframe
+-org.chromium.android_webview.test.LoadDataWithBaseUrlTest.testXhrForCustomSchemeUrl
 -org.chromium.android_webview.test.LoadDataWithBaseUrlTest.testXhrForHttpSchemeUrl
 
 # https://crbug.com/893581