The test that's failing is PasswordManagerBrowserTestBase.InFrameNavigationDoesNotClearPopupState. It first started in https://build.chromium.org/p/chromium.mac/builders/Mac10.11%20Tests/builds/6472, it's a seg fault, and it looks like it's a little flaky (there are occasional builds that are succeeding).

The most relevant CL I could find vaguely in range is https://codereview.chromium.org/2630423002. I'm not confident enough that this is the culprit to revert.

cc'ing owner of CL and owners of the test to see if someone can find a fix.

Jan 16 21:26:58  browser_tests[53445] <Error>: CGAffineTransformInvert: singular matrix.
BrowserTestBase received signal: Segmentation fault: 11. Backtrace:
0   browser_tests                       0x000000010f960b83 _ZN4base5debug10StackTraceC1Ev + 19
1   browser_tests                       0x00000001100703aa _ZN7content12_GLOBAL__N_1L27DumpStackTraceSignalHandlerEi + 202
2   libsystem_platform.dylib            0x00007fff9f28152a _sigtramp + 26
3   ???                                 0x00007fff5266e622 0x0 + 140734575863330
4   browser_tests                       0x000000010f760b15 _ZN8autofill5mojom33PasswordManagerDriverStubDispatch6AcceptEPNS0_21PasswordManagerDriverEPN4mojo8internal20SerializationContextEPNS4_7MessageE + 2821
5   browser_tests                       0x0000000110b546ca _ZN4mojo8internal15MultiplexRouter22ProcessIncomingMessageEPNS_7MessageENS1_18ClientCallBehaviorEPN4base22SingleThreadTaskRunnerE + 410
6   browser_tests                       0x0000000110b5420c _ZN4mojo8internal15MultiplexRouter6AcceptEPNS_7MessageE + 108
7   browser_tests                       0x0000000110b4e38a _ZN4mojo9Connector17ReadSingleMessageEPj + 170
8   browser_tests                       0x0000000110b4e661 _ZN4mojo9Connector20OnWatcherHandleReadyEj + 81
9   browser_tests                       0x0000000110b5a96b _ZN4mojo7Watcher13OnHandleReadyEj + 75
10  browser_tests                       0x000000010f961151 _ZN4base5debug13TaskAnnotator7RunTaskEPKcPNS_11PendingTaskE + 225
11  browser_tests                       0x000000010f98675b _ZN4base11MessageLoop7RunTaskEPNS_11PendingTaskE + 507
12  browser_tests                       0x000000010f986aac _ZN4base11MessageLoop21DeferOrRunPendingTaskENS_11PendingTaskE + 44
13  browser_tests                       0x000000010f986e63 _ZN4base11MessageLoop6DoWorkEv + 371
14  browser_tests                       0x000000010f98a13a _ZN4base24MessagePumpCFRunLoopBase7RunWorkEv + 42
15  browser_tests                       0x000000010f97ab0a _ZN4base3mac15CallWithEHFrameEU13block_pointerFvvE + 10
16  browser_tests                       0x000000010f989bb4 _ZN4base24MessagePumpCFRunLoopBase13RunWorkSourceEPv + 68
17  CoreFoundation                      0x00007fff957e7881 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
18  CoreFoundation                      0x00007fff957c6fbc __CFRunLoopDoSources0 + 556
19  CoreFoundation                      0x00007fff957c64df __CFRunLoopRun + 927
20  CoreFoundation                      0x00007fff957c5ed8 CFRunLoopRunSpecific + 296
21  HIToolbox                           0x00007fff93525935 RunCurrentEventLoopInMode + 235
22  HIToolbox                           0x00007fff9352576f ReceiveNextEventCommon + 432
23  HIToolbox                           0x00007fff935255af _BlockUntilNextEventMatchingListInModeWithFilter + 71
24  AppKit                              0x00007fff98994df6 _DPSNextEvent + 1067
25  AppKit                              0x00007fff98994226 -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 454
26  browser_tests                       0x000000010fa7f480 __71-[BrowserCrApplication nextEventMatchingMask:untilDate:inMode:dequeue:]_block_invoke + 64
27  browser_tests                       0x000000010f97ab0a _ZN4base3mac15CallWithEHFrameEU13block_pointerFvvE + 10
28  browser_tests                       0x000000010fa7f3b9 -[BrowserCrApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 169
29  AppKit                              0x00007fff98988d80 -[NSApplication run] + 682
30  browser_tests                       0x000000010f98a9ae _ZN4base24MessagePumpNSApplication5DoRunEPNS_11MessagePump8DelegateE + 334
31  browser_tests                       0x000000010f989ffc _ZN4base24MessagePumpCFRunLoopBase3RunEPNS_11MessagePump8DelegateE + 92
32  browser_tests                       0x000000010f98644e _ZN4base11MessageLoop10RunHandlerEv + 94
33  browser_tests                       0x000000010f9aaad3 _ZN4base7RunLoop3RunEv + 115
34  browser_tests                       0x00000001103facf1 _ZN3net11test_server18EmbeddedTestServer25PostTaskToIOThreadAndWaitERKN4base8CallbackIFvvELNS2_8internal8CopyModeE1ELNS5_10RepeatModeE1EEE + 241
35  browser_tests                       0x00000001103f996f _ZN3net11test_server18EmbeddedTestServer28ShutdownAndWaitUntilCompleteEv + 95
36  browser_tests                       0x00000001141981a4 _ZN30PasswordManagerBrowserTestBase20TearDownOnMainThreadEv + 20
37  browser_tests                       0x000000010fa1aecc _ZN20InProcessBrowserTest23RunTestOnMainThreadLoopEv + 1388
38  browser_tests                       0x0000000110070116 _ZN7content15BrowserTestBase28ProxyRunTestOnMainThreadLoopEv + 278
39  browser_tests                       0x000000010fa8430d _ZN22ChromeBrowserMainParts25PreMainMessageLoopRunImplEv + 4253
40  browser_tests                       0x000000010fa8316e _ZN22ChromeBrowserMainParts21PreMainMessageLoopRunEv + 62
41  browser_tests                       0x000000010f15b133 _ZN7content15BrowserMainLoop21PreMainMessageLoopRunEv + 67
42  browser_tests                       0x000000010f475c86 _ZN7content17StartupTaskRunner14RunAllTasksNowEv + 38
43  browser_tests                       0x000000010f159422 _ZN7content15BrowserMainLoop18CreateStartupTasksEv + 658
44  browser_tests                       0x000000010f15de0b _ZN7content21BrowserMainRunnerImpl10InitializeERKNS_18MainFunctionParamsE + 683
45  browser_tests                       0x000000010f156db4 _ZN7content11BrowserMainERKNS_18MainFunctionParamsE + 100
46  browser_tests                       0x000000010f947230 _ZN7content21ContentMainRunnerImpl3RunEv + 368
47  browser_tests                       0x000000010f946436 _ZN7content11ContentMainERKNS_17ContentMainParamsE + 54
48  browser_tests                       0x000000011006fe22 _ZN7content15BrowserTestBase5SetUpEv + 1906
49  browser_tests                       0x000000010fa19d24 _ZN20InProcessBrowserTest5SetUpEv + 340
50  browser_tests                       0x00000001107890fb _ZN7testing4Test3RunEv + 299
51  browser_tests                       0x0000000110789fa0 _ZN7testing8TestInfo3RunEv + 576
52  browser_tests                       0x000000011078a657 _ZN7testing8TestCase3RunEv + 455
53  browser_tests                       0x0000000110790857 _ZN7testing8internal12UnitTestImpl11RunAllTestsEv + 967
54  browser_tests                       0x0000000110790459 _ZN7testing8UnitTest3RunEv + 265
55  browser_tests                       0x000000010fa2f3d5 _ZN4base9TestSuite3RunEv + 133
56  browser_tests                       0x000000010f953a8f _ZN21ChromeTestSuiteRunner12RunTestSuiteEiPPc + 31
57  browser_tests                       0x00000001100a9eee _ZN7content11LaunchTestsEPNS_20TestLauncherDelegateEiiPPc + 302
58  browser_tests                       0x000000010f953a1a main + 90
59  libdyld.dylib                       0x00007fff922385ad start + 1

I also noticed that PasswordManagerBrowserTestBase.InFrameNavigationDoesNotClearPopupState is failing intermittently on other mac builders, for example:

https://uberchromegw.corp.google.com/i/chromium.mac/builders/Mac10.9%20Tests/builds/34787

Thanks for bringing this to my attention. Did you mean to link to http://crrev.com/2607413003? This is the last CL that touched the test file. 

Judging by the stack trace this looks unrelated, and the test seems flaky indeed. As of now the last 6 Mac 10.11 Builds and the last 9 Mac 10.9 Builds have been successful.

However, I will keep a look at it.

The culprit must be one of the 4 changes in the build that was linked by meade@ above: https://build.chromium.org/p/chromium.mac/builders/Mac10.11%20Tests/builds/6472. The first 2 are unlikely to influence the test.

Additionally, on Mac10.10 the test also flakes, and the list of culprits has only 2 CLs (which match the 4 minus 2 unlikely ones above). Here they are: https://chromium.googlesource.com/chromium/src/+log/56732c5de584ab7b38ba694204beaf038669cf9c%5E..5fe8de4d4823f0b09ce11446cc913e485a70366b?pretty=fuller

I am inclined to think that Emily's (estark@) CL (https://codereview.chromium.org/2629663002) is the cause, and it helped to uncover some problem. Dear PasswordManager team, can you please figure out whether changing HttpFormWarning feature could influence your test?

Meanwhile, let me try to revert Emily's CL and see how it goes.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b850623ef5632ca96ffcc65c13d036ca0ab3271d

commit b850623ef5632ca96ffcc65c13d036ca0ab3271d
Author: pkalinnikov <pkalinnikov@chromium.org>
Date: Tue Jan 17 13:05:15 2017

Revert of Enable HttpFormWarning in fieldtrial_testing_config.json (patchset #1 id:1 of https://codereview.chromium.org/2629663002/ )

Reason for revert:
Likely causing flakiness of PasswordManagerBrowserTestBase.InFrameNavigationDoesNotClearPopupState on Mac10.11/Mac10.10/Mac10.9 Tests.

Original issue's description:
> Enable HttpFormWarning in fieldtrial_testing_config.json
>
> BUG= 674320 
>
> Review-Url: https://codereview.chromium.org/2629663002
> Cr-Commit-Position: refs/heads/master@{#443946}
> Committed: https://chromium.googlesource.com/chromium/src/+/56732c5de584ab7b38ba694204beaf038669cf9c

TBR=jwd@chromium.org,estark@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG= 674320 , 681710 

Review-Url: https://codereview.chromium.org/2634093003
Cr-Commit-Position: refs/heads/master@{#444036}

[modify] https://crrev.com/b850623ef5632ca96ffcc65c13d036ca0ab3271d/testing/variations/fieldtrial_testing_config.json

Reverting the CL has stopped the flakiness: https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=PasswordManagerBrowserTestBase.InFrameNavigationDoesNotClearPopupState.

Please address the issue with HttpFormWarning feature. I am adding Emily to CC and dropping the Sheriff label.

https://codereview.chromium.org/2641653002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/921882bd5ee50f1e59288a51f0fd018261f3ffc2

commit 921882bd5ee50f1e59288a51f0fd018261f3ffc2
Author: estark <estark@chromium.org>
Date: Wed Jan 18 16:13:48 2017

Make ObservingAutofillClient a WebContentsUserData

ObservingAutofillClient was triggering a stack-use-after-return under certain
circumstances (see bug), presumably because the WebContents and
ContentPasswordManagerDriver stayed alive after the local
ObservingAutofillClient variable was deleted when the test body returned.

This change makes ObservingAutofillClient a WebContentsUserData so that it
matches the lifetime of the WebContents which outlives the
ContentPasswordManagerDriver that uses it. This matches how the production code
works as well (ChromeAutofillClient is a WebContentsUserData).

BUG= 681710 

Review-Url: https://codereview.chromium.org/2641653002
Cr-Commit-Position: refs/heads/master@{#444380}

[modify] https://crrev.com/921882bd5ee50f1e59288a51f0fd018261f3ffc2/chrome/browser/password_manager/password_manager_browsertest.cc

Commit in comment 14 should fix it; I'll reland my commit that triggered the flakiness (https://codereview.chromium.org/2629663002/) and keep an eye on the flakiness dashboard.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c890ad04b852fcc9834b988cf896534228144bb4

commit c890ad04b852fcc9834b988cf896534228144bb4
Author: estark <estark@chromium.org>
Date: Wed Jan 18 17:10:16 2017

Reland of Enable HttpFormWarning in fieldtrial_testing_config.json (patchset #1 id:1 of https://codereview.chromium.org/2634093003/ )

Reason for revert:
This seemed to trigger a previously existing test issue, which I fixed in https://bugs.chromium.org/p/chromium/issues/detail?id=681710&desc=2#c14. I'll keep an eye on the flakiness dashboard after relanding this to make sure it's fixed.

Original issue's description:
> Revert of Enable HttpFormWarning in fieldtrial_testing_config.json (patchset #1 id:1 of https://codereview.chromium.org/2629663002/ )
>
> Reason for revert:
> Likely causing flakiness of PasswordManagerBrowserTestBase.InFrameNavigationDoesNotClearPopupState on Mac10.11/Mac10.10/Mac10.9 Tests.
>
> Original issue's description:
> > Enable HttpFormWarning in fieldtrial_testing_config.json
> >
> > BUG= 674320 
> >
> > Review-Url: https://codereview.chromium.org/2629663002
> > Cr-Commit-Position: refs/heads/master@{#443946}
> > Committed: https://chromium.googlesource.com/chromium/src/+/56732c5de584ab7b38ba694204beaf038669cf9c
>
> TBR=jwd@chromium.org,estark@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG= 674320 , 681710 
>
> Review-Url: https://codereview.chromium.org/2634093003
> Cr-Commit-Position: refs/heads/master@{#444036}
> Committed: https://chromium.googlesource.com/chromium/src/+/b850623ef5632ca96ffcc65c13d036ca0ab3271d

TBR=jwd@chromium.org,pkalinnikov@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG= 674320 , 681710 

Review-Url: https://codereview.chromium.org/2641893002
Cr-Commit-Position: refs/heads/master@{#444404}

[modify] https://crrev.com/c890ad04b852fcc9834b988cf896534228144bb4/testing/variations/fieldtrial_testing_config.json