content_browsertests failing on chromium.memory/Mac ASan 64 Tests (1)

Builders failed on Mac ASan 64 Tests (1):  https://build.chromium.org/p/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29

Within the last ~40 builds, SnapshotBrowserTest.SyncMultiWindowTest failed 5 times:
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/34998
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/35009
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/35019
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/35026
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/35028

Especially notable:
===================
It complains in every case about an "Uncaught ReferenceError: fillWithColor is not defined".


Repeated failure log:
=====================

DevTools listening on ws://127.0.0.1:53861/devtools/browser/9987350e-e0ee-4f79-afdf-9dd032f646fe
[8565:7431:1012/034036.280562:53586908345643:WARNING:vt_video_decode_accelerator_mac.cc(178)] Failed to create VTDecompressionSession: Error Domain=NSOSStatusErrorDomain Code=-8973 "The operation couldn?t be completed. (OSStatus error -8973.)" (codecOpenErr) (-8973)
[8565:7431:1012/034036.282290:53586910067352:WARNING:vt_video_decode_accelerator_mac.cc(200)] Failed to create hardware VideoToolbox session
[8565:7431:1012/034036.391668:53587019447881:ERROR:vt_video_encode_accelerator_mac.cc(495)]  VTCompressionSessionCreate failed: -12908
[8561:7431:1012/034036.899154:53587526951199:INFO:CONSOLE(1)] "Uncaught ReferenceError: fillWithColor is not defined", source: http://127.0.0.1:53863/test (1)
BrowserTestBase received signal: Terminated: 15. Backtrace:
0   content_browsertests                0x0000000108f2e8ac base::debug::StackTrace::StackTrace(unsigned long) + 28
1   content_browsertests                0x00000001083cec2f content::(anonymous namespace)::DumpStackTraceSignalHandler(int) + 479
2   libsystem_platform.dylib            0x00007fff928485aa _sigtramp + 26
3   ???                                 0x0000000000000000 0x0 + 0
4   CoreFoundation                      0x00007fff96cc3f15 __CFRunLoopServiceMachPort + 181
5   CoreFoundation                      0x00007fff96cc3539 __CFRunLoopRun + 1161
6   CoreFoundation                      0x00007fff96cc2e75 CFRunLoopRunSpecific + 309
7   HIToolbox                           0x00007fff95152a0d RunCurrentEventLoopInMode + 226
8   HIToolbox                           0x00007fff951527b7 ReceiveNextEventCommon + 479
9   HIToolbox                           0x00007fff951525bc _BlockUntilNextEventMatchingListInModeWithFilter + 65
10  AppKit                              0x00007fff8f39d24e _DPSNextEvent + 1434
11  AppKit                              0x00007fff8f39c89b -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
12  AppKit                              0x00007fff8f39099c -[NSApplication run] + 553
13  content_browsertests                0x0000000108fce93f base::MessagePumpNSApplication::DoRun(base::MessagePump::Delegate*) + 1007
14  content_browsertests                0x0000000108fc8d51 base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 401
15  content_browsertests                0x0000000108fc0436 base::MessageLoop::Run() + 470
16  content_browsertests                0x0000000109041af3 base::RunLoop::Run() + 387
17  content_browsertests                0x000000010844013c content::MessageLoopRunner::Run() + 380
18  content_browsertests                0x00000001083da82a content::DOMMessageQueue::WaitForMessage(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) + 634
19  content_browsertests                0x00000001083d680f content::(anonymous namespace)::ExecuteScriptHelper(content::RenderFrameHost*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool, std::__1::unique_ptr<base::Value, std::__1::default_delete<base::Value> >*) + 1023
20  content_browsertests                0x00000001083d54a0 content::ExecuteScriptAndExtractString(content::ToRenderFrameHost const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) + 352
21  content_browsertests                0x0000000102cf4405 content::SnapshotBrowserTest_SyncMultiWindowTest_Test::RunTestOnMainThread() + 5461
22  content_browsertests                0x00000001083ce4c9 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() + 1065
23  content_browsertests                0x00000001085ab6c5 content::ShellBrowserMainParts::PreMainMessageLoopRun() + 821
24  content_browsertests                0x0000000104a26b4e content::BrowserMainLoop::PreMainMessageLoopRun() + 350
25  content_browsertests                0x0000000105917b32 content::StartupTaskRunner::RunAllTasksNow() + 466
26  content_browsertests                0x0000000104a224a7 content::BrowserMainLoop::CreateStartupTasks() + 1479
27  content_browsertests                0x0000000104a30236 content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&) + 1318
28  content_browsertests                0x00000001085aa383 ShellBrowserMain(content::MainFunctionParams const&, std::__1::unique_ptr<content::BrowserMainRunner, std::__1::default_delete<content::BrowserMainRunner> > const&) + 275
29  content_browsertests                0x00000001084e16c0 content::ShellMainDelegate::RunProcess(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, content::MainFunctionParams const&) + 416
30  content_browsertests                0x00000001046ad52c content::RunNamedProcessTypeMain(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, content::MainFunctionParams const&, content::ContentMainDelegate*) + 1244
31  content_browsertests                0x00000001046aef79 content::ContentMainRunnerImpl::Run() + 1337
32  content_browsertests                0x000000010cf1543c service_manager::Main(service_manager::MainParams const&) + 5596
33  content_browsertests                0x00000001046acf79 content::ContentMain(content::ContentMainParams const&) + 345
34  content_browsertests                0x00000001083cd560 content::BrowserTestBase::SetUp() + 4592
35  content_browsertests                0x000000010839a023 content::ContentBrowserTest::SetUp() + 1379
36  content_browsertests                0x0000000103240060 testing::Test::Run() + 256
37  content_browsertests                0x0000000103241e34 testing::TestInfo::Run() + 884
38  content_browsertests                0x0000000103243167 testing::TestCase::Run() + 967
39  content_browsertests                0x0000000103257bb7 testing::internal::UnitTestImpl::RunAllTests() + 2439
40  content_browsertests                0x000000010325717a testing::UnitTest::Run() + 298
41  content_browsertests                0x00000001084781a7 base::TestSuite::Run() + 503
42  content_browsertests                0x00000001083a831a content::ContentTestLauncherDelegate::RunTestSuite(int, char**) + 234
43  content_browsertests                0x000000010842b804 content::LaunchTests(content::TestLauncherDelegate*, unsigned long, int, char**) + 1012
44  content_browsertests                0x00000001083a81b8 main + 248
45  libdyld.dylib                       0x00007fff8bb425fd start + 1
[8567:7175:1012/034135.795277:53646423064983:WARNING:gpu.cc(144)] Encountered error while establishing gpu channel.