I've CQ'd a CL to disable this test entirely, as it fails on various forms of Mac, Win and Linux.

Related to: https://bugs.chromium.org/p/chromium/issues/detail?id=771119

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8e969b88c3c55aff7f0bae87ce578e1f99645f48

commit 8e969b88c3c55aff7f0bae87ce578e1f99645f48
Author: W. James MacLean <wjmaclean@chromium.org>
Date: Fri Oct 06 14:25:34 2017

Disable AsyncMultiWindowTest.

This test is also timing out on non-debug bots.

Bug:  772379 
Change-Id: I9bc0fff04a9629037dec631b09279c2b01f9cc4e

TBR=boliu@chromium.org,kbr@chromium.org

Change-Id: I9bc0fff04a9629037dec631b09279c2b01f9cc4e
Reviewed-on: https://chromium-review.googlesource.com/704057
Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507058}
[modify] https://crrev.com/8e969b88c3c55aff7f0bae87ce578e1f99645f48/content/browser/snapshot_browsertest.cc

It looks like the race condition described in  Issue 772650  is still happening on these ASAN bots. The stack trace is as follows:

[12419:7175:1006/054943.399124:76813781488708:INFO:CONSOLE(1)] "Uncaught ReferenceError: fillWithColor is not defined", source: http://127.0.0.1:58377/test (1)
BrowserTestBase received signal: Terminated: 15. Backtrace:
0   content_browsertests                0x0000000107d417ec base::debug::StackTrace::StackTrace(unsigned long) + 28
1   content_browsertests                0x000000010723367f content::(anonymous namespace)::DumpStackTraceSignalHandler(int) + 479
2   libsystem_platform.dylib            0x00007fff8e8d55aa _sigtramp + 26
3   ???                                 0x0000000000000000 0x0 + 0
4   CoreFoundation                      0x00007fff92d50f15 __CFRunLoopServiceMachPort + 181
5   CoreFoundation                      0x00007fff92d50539 __CFRunLoopRun + 1161
6   CoreFoundation                      0x00007fff92d4fe75 CFRunLoopRunSpecific + 309
7   HIToolbox                           0x00007fff911dfa0d RunCurrentEventLoopInMode + 226
8   HIToolbox                           0x00007fff911df7b7 ReceiveNextEventCommon + 479
9   HIToolbox                           0x00007fff911df5bc _BlockUntilNextEventMatchingListInModeWithFilter + 65
10  AppKit                              0x00007fff8b42a24e _DPSNextEvent + 1434
11  AppKit                              0x00007fff8b42989b -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
12  AppKit                              0x00007fff8b41d99c -[NSApplication run] + 553
13  content_browsertests                0x0000000107ddba2f base::MessagePumpNSApplication::DoRun(base::MessagePump::Delegate*) + 1007
14  content_browsertests                0x0000000107dd5e41 base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 401
15  content_browsertests                0x0000000107dcbae6 base::MessageLoop::Run() + 470
16  content_browsertests                0x0000000107e4d983 base::RunLoop::Run() + 387
17  content_browsertests                0x00000001072a089c content::MessageLoopRunner::Run() + 380
18  content_browsertests                0x000000010723ee1f content::DOMMessageQueue::WaitForMessage(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) + 543
19  content_browsertests                0x000000010723ae9f 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                0x0000000107239b30 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                0x0000000101ed56db content::SnapshotBrowserTest_AsyncMultiWindowTest_Test::RunTestOnMainThread() + 6827
22  content_browsertests                0x0000000107232f19 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() + 1065
23  content_browsertests                0x00000001074051f9 content::ShellBrowserMainParts::PreMainMessageLoopRun() + 681
24  content_browsertests                0x00000001039497ae content::BrowserMainLoop::PreMainMessageLoopRun() + 350
25  content_browsertests                0x00000001047d27a7 content::StartupTaskRunner::RunAllTasksNow() + 327
26  content_browsertests                0x0000000103944eb7 content::BrowserMainLoop::CreateStartupTasks() + 1479

Investigating.

 Issue 772650  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/745308be7bd9df53c1834d674220d885adf40b00

commit 745308be7bd9df53c1834d674220d885adf40b00
Author: Kenneth Russell <kbr@chromium.org>
Date: Thu Oct 12 22:51:46 2017

Wait for subordinate windows to be ready in SnapshotBrowserTest.

In order to force all the windows to share the same renderer process,
the test calls window.open() from JavaScript, which doesn't have the
same synchronization guarantees as content_browser_test_utils'
NavigateToURL. Wait for the script to execute in each window before
proceeding with the test.

BUG= 772379 

Change-Id: Id5aff8aca03e22c65d06e5ed35c4aeff13997ac2
Reviewed-on: https://chromium-review.googlesource.com/714684
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508514}
[modify] https://crrev.com/745308be7bd9df53c1834d674220d885adf40b00/content/browser/snapshot_browsertest.cc

 Issue 774050  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/064a1f3a5974481ae060d829beeb82661f922e80

commit 064a1f3a5974481ae060d829beeb82661f922e80
Author: Kenneth Russell <kbr@chromium.org>
Date: Fri Oct 13 18:10:53 2017

Re-enable SnapshotBrowserTest.SyncMultiWindowTest.

The fix that just landed in  Issue 772379  should make this test
reliable everywhere.

BUG= 771119 ,  772379 
TBR=fhorschig@chromium.org

Change-Id: I6a6a17f98e4b4c33d3bafa81253fc0cf46591657
Reviewed-on: https://chromium-review.googlesource.com/717698
Reviewed-by: Friedrich Horschig <fhorschig@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508755}
[modify] https://crrev.com/064a1f3a5974481ae060d829beeb82661f922e80/content/browser/snapshot_browsertest.cc

I believe this test is de-flaked at this point. Please reopen if you find this isn't the case. Thanks.

Deleted the previous comment since the failure was on debug build.