First failure at:
https://ci.chromium.org/buildbot/chromium.android/Marshmallow%2064%20bit%20Tester/17935

From the CL range:
http://test-results.appspot.com/revision_range?start=522256&end=522276

The following seems related
r522268 Add Chrome Policy Blacklist support for Network Service

+dougt can you have a look?

Error looks like:

java.lang.AssertionError: expected:<-6> but was:<-1>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:834)
	at org.junit.Assert.assertEquals(Assert.java:645)
	at org.junit.Assert.assertEquals(Assert.java:631)
	at org.chromium.android_webview.test.PolicyUrlFilteringTest.testBlacklistedUrl(PolicyUrlFilteringTest.java:91)
	at java.lang.reflect.Method.invoke(Native Method)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:52)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.chromium.base.test.ScreenshotOnFailureStatement.evaluate(ScreenshotOnFailureStatement.java:37)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.chromium.android_webview.test.AwActivityTestRule$1.evaluate(AwActivityTestRule.java:72)
	at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55)
	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:270)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.chromium.base.test.BaseJUnit4ClassRunner.runChild(BaseJUnit4ClassRunner.java:184)
	at org.chromium.android_webview.test.AwJUnit4ClassRunner.runChild(AwJUnit4ClassRunner.java:66)
	at org.chromium.android_webview.test.AwJUnit4ClassRunner.runChild(AwJUnit4ClassRunner.java:33)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.chromium.base.test.BaseJUnit4ClassRunner.run(BaseJUnit4ClassRunner.java:166)
	at org.junit.runners.Suite.runChild(Suite.java:128)
	at org.junit.runners.Suite.runChild(Suite.java:27)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
	at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
	at org.chromium.base.test.BaseChromiumAndroidJUnitRunner.onStart(BaseChromiumAndroidJUnitRunner.java:99)
	at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1879)
Searching for native crashes in: /b/swarming/w/itaQz8EQ/tmpcafJJl
Unknown Android release, consider passing --packed-lib.
Reading Android symbols from: /b/swarming/w/ir
Searching for Chrome symbols from within: /b/swarming/w/ir/out/Debug/lib.unstripped:/b/swarming/w/ir/out/Debug/lib:/b/swarming/w/ir/out/Debug

Failure is pretty consistent, for the moment I'm going to do a speculative revert of r522268.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/034134229bfcfe39482304614c615b826979d822

commit 034134229bfcfe39482304614c615b826979d822
Author: Juan Antonio Navarro Pérez <perezju@chromium.org>
Date: Thu Dec 07 15:05:45 2017

Revert "Add Chrome Policy Blacklist support for Network Service"

This reverts commit 574253081eebc50b94efb2e1d46fc83d2a75c8f1.

Reason for revert: Speculative revert to fix  issue 792868 .

Original change's description:
> Add Chrome Policy Blacklist support for Network Service
> 
> In this CL, we create a new implementation of NavigationThrottle, called
> PolicyBlacklistNavigationThrottle in which we call into a
> policy::URLBlacklistManager implementation during calls to WillStartRequest().
> If the requested URL is in the blocklist, we’d return CANCEL otherwise PROCEED.
> 
> This CL also introduces a KeyedService for accessing the
> policy::URLBlacklistManager.
> 
> Bug:  756642 
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo;master.tryserver.chromium.linux:linux_site_isolation
> Change-Id: I2d9ca0982e78b03be191b67e61eea14764150e68
> Reviewed-on: https://chromium-review.googlesource.com/745326
> Commit-Queue: Doug Turner <dougt@chromium.org>
> Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
> Reviewed-by: Bo <boliu@chromium.org>
> Reviewed-by: John Abd-El-Malek <jam@chromium.org>
> Reviewed-by: Ken Rockot <rockot@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#522268}

TBR=pastarmovj@chromium.org,nasko@chromium.org,jam@chromium.org,boliu@chromium.org,rockot@chromium.org,clamy@chromium.org,dougt@chromium.org,cjennyc28@gmail.com

Change-Id: I09dad40ad0dffa4cf7accfc0cd2dbb722b1c651b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  756642 ,  792868 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo;master.tryserver.chromium.linux:linux_site_isolation
Reviewed-on: https://chromium-review.googlesource.com/814394
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Juan Antonio Navarro Pérez <perezju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522427}
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/BUILD.gn
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/DEPS
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/aw_browser_context.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/aw_browser_context.h
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/aw_content_browser_client.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/net/aw_network_delegate.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/android_webview/browser/net/aw_network_delegate.h
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/BUILD.gn
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/DEPS
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/chrome_content_browser_client.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/net/chrome_network_delegate.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/net/chrome_network_delegate.h
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/profiles/profile_io_data.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/chrome/browser/profiles/profile_io_data.h
[delete] https://crrev.com/1419427e917eb6110885aafbe64966585287c1d4/components/policy/content/BUILD.gn
[delete] https://crrev.com/1419427e917eb6110885aafbe64966585287c1d4/components/policy/content/DEPS
[delete] https://crrev.com/1419427e917eb6110885aafbe64966585287c1d4/components/policy/content/policy_blacklist_navigation_throttle.cc
[delete] https://crrev.com/1419427e917eb6110885aafbe64966585287c1d4/components/policy/content/policy_blacklist_navigation_throttle.h
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/components/policy/core/browser/url_blacklist_manager.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/components/policy/core/browser/url_blacklist_manager.h
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/components/policy/core/browser/url_blacklist_manager_unittest.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/content/browser/frame_host/navigation_request.cc
[modify] https://crrev.com/034134229bfcfe39482304614c615b826979d822/testing/buildbot/filters/mojo.fyi.network_browser_tests.filter

Looks like the revert cleared this up.

 Issue 793039  has been merged into this issue.