test output:

[ RUN      ] ExtensionApiTabTest.OnUpdatedDiscardedState
[13867:13954:0509/122807.992842:ERROR:account_manager.cc(37)] Failed to read tokens file
[13867:13867:0509/122808.037174:WARNING:user_session_manager.cc(1096)] Attempting to save user password for non enterprise user.
[13867:13867:0509/122814.818060:INFO:CONSOLE(0)] "[SUCCESS] setupWindow", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[13867:13867:0509/122815.634314:INFO:CONSOLE(0)] "[SUCCESS] discard", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[13867:13867:0509/122816.124828:INFO:CONSOLE(0)] "Unchecked runtime.lastError while running tabs.reload: No tab with id: 5.
    at reload (chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.js:73:17)", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
BrowserTestBase received signal: Terminated. Backtrace:
    #0 0x000000a805d1 in __interceptor_backtrace /b/build/slave/linux_upload_clang/build/src/third_party/llvm/compiler-rt/lib/msan/../sanitizer_common/sanitizer_common_interceptors.inc:3980:13
    #1 0x000012fdd45f in base::debug::StackTrace::StackTrace(unsigned long) ./../../base/debug/stack_trace_posix.cc:808:41
    #2 0x000014a4a512 in content::(anonymous namespace)::DumpStackTraceSignalHandler(int) ./../../content/public/test/browser_test_base.cc:86:5
    #3 0x000000aa7dc9 in SignalHandler(int) /b/build/slave/linux_upload_clang/build/src/third_party/llvm/compiler-rt/lib/msan/msan_interceptors.cc:995:3
    #4 0x7f761fa39cb0 in killpg ??:?
    #5 0x7f761fa39cb0 in ?? ??:0
    #6 0x7f761fb016d3 in epoll_wait /build/eglibc-ripdx6/eglibc-2.19/misc/../sysdeps/unix/syscall-template.S:81:0
    #7 0x000000a69694 in __interceptor_epoll_wait /b/build/slave/linux_upload_clang/build/src/third_party/llvm/compiler-rt/lib/msan/msan_interceptors.cc:862:13
    #8 0x000016b63d0b in epoll_dispatch ./../../base/third_party/libevent/epoll.c:198:8
    #9 0x000016b5701b in event_base_loop ./../../base/third_party/libevent/event.c:512:9
    #10 0x00001301ec88 in base::MessagePumpLibevent::Run(base::MessagePump::Delegate*) ./../../base/message_loop/message_pump_libevent.cc:247:9
    #11 0x000012e35860 in base::RunLoop::Run() ./../../base/run_loop.cc:131:14
    #12 0x000014b01d65 in content::RunThisRunLoop(base::RunLoop*) ./../../content/public/test/test_utils.cc:128:13
    #13 0x00002b6d4d9d in extensions::ResultCatcher::GetNextResult() ./../../extensions/test/result_catcher.cc:35:5
    #14 0x000004ca4deb in ExtensionApiTest::RunExtensionTestImpl(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> > const&, char const*, int) ./../../chrome/browser/extensions/extension_apitest.cc:393:16
    #15 0x000004f337a0 in ExtensionApiTabTest_OnUpdatedDiscardedState_Test::RunTestOnMainThread() ./../../chrome/browser/extensions/extension_tabs_apitest.cc:277:3
    #16 0x000014a498a0 in content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() ./../../content/public/test/browser_test_base.cc:383:5
    #17 0x0000133782d7 in Run ./../../base/callback.h:125:12
    #18 0x0000133782d7 in ChromeBrowserMainParts::PreMainMessageLoopRunImpl() ./../../chrome/browser/chrome_browser_main.cc:2078:0
    #19 0x000013373ca0 in ChromeBrowserMainParts::PreMainMessageLoopRun() ./../../chrome/browser/chrome_browser_main.cc:1470:18
    #20 0x00000743a995 in chromeos::ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun() ./../../chrome/browser/chromeos/chrome_browser_main_chromeos.cc:715:32
    #21 0x00000bb9a5db in content::BrowserMainLoop::PreMainMessageLoopRun() ./../../content/browser/browser_main_loop.cc:959:13
    #22 0x00000d07bca1 in Run ./../../base/callback.h:125:12
    #23 0x00000d07bca1 in content::StartupTaskRunner::RunAllTasksNow() ./../../content/browser/startup_task_runner.cc:44:0
    #24 0x00000bb92d48 in content::BrowserMainLoop::CreateStartupTasks() ./../../content/browser/browser_main_loop.cc:872:25
    #25 0x00000bba5aa7 in content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&) ./../../content/browser/browser_main_runner.cc:139:17
    #26 0x00000bb87216 in content::BrowserMain(content::MainFunctionParams const&) ./../../content/browser/browser_main.cc:42:32
    #27 0x000012b40273 in content::RunNamedProcessTypeMain(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, content::MainFunctionParams const&, content::ContentMainDelegate*) ./../../content/app/content_main_runner.cc:640:14
    #28 0x000012b4384f in content::ContentMainRunnerImpl::Run() ./../../content/app/content_main_runner.cc:943:12
    #29 0x00001c7e8214 in service_manager::Main(service_manager::MainParams const&) ./../../services/service_manager/embedder/main.cc:452:29
    #30 0x000012b39e68 in content::ContentMain(content::ContentMainParams const&) ./../../content/app/content_main.cc:19:10
    #31 0x000014a47d62 in content::BrowserTestBase::SetUp() ./../../content/public/test/browser_test_base.cc:321:3
    #32 0x0000132209af in InProcessBrowserTest::SetUp() ./../../chrome/test/base/in_process_browser_test.cc:243:20
    #33 0x000008939bf6 in testing::Test::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:0:0
    #34 0x00000893dc1c in testing::TestInfo::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:2667:11
    #35 0x00000893f69a in testing::TestCase::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:2785:28
    #36 0x000008975f55 in testing::internal::UnitTestImpl::RunAllTests() ./../../third_party/googletest/src/googletest/src/gtest.cc:5047:43
    #37 0x000008974843 in testing::UnitTest::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:0:0
    #38 0x0000132875a7 in RUN_ALL_TESTS ./../../third_party/googletest/src/googletest/include/gtest/gtest.h:2329:46
    #39 0x0000132875a7 in base::TestSuite::Run() ./../../base/test/test_suite.cc:275:0
    #40 0x000012cbdf64 in ChromeTestSuiteRunner::RunTestSuite(int, char**) ./../../chrome/test/base/chrome_test_launcher.cc:65:38
    #41 0x000014af1a85 in content::LaunchTests(content::TestLauncherDelegate*, unsigned long, int, char**) ./../../content/public/test/test_launcher.cc:625:31
    #42 0x000012cbf6c8 in LaunchChromeTests(unsigned long, content::TestLauncherDelegate*, int, char**) ./../../chrome/test/base/chrome_test_launcher.cc:170:10
    #43 0x000012cbdd50 in main ./../../chrome/test/base/browser_tests_main_chromeos.cc:21:10
    #44 0x7f761fa24f45 in __libc_start_main /build/eglibc-ripdx6/eglibc-2.19/csu/libc-start.c:287:0
    #45 0x000000a43c6a in _start ??:0:0
[ RUN      ] ExtensionApiTabTest.OnUpdatedDiscardedState
[11198:11217:0509/130258.218505:ERROR:account_manager.cc(37)] Failed to read tokens file
[11198:11198:0509/130258.245410:WARNING:user_session_manager.cc(1096)] Attempting to save user password for non enterprise user.
[11198:11198:0509/130302.106007:INFO:CONSOLE(0)] "[SUCCESS] setupWindow", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[11198:11198:0509/130302.410119:INFO:CONSOLE(0)] "[SUCCESS] discard", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[11198:11198:0509/130302.636789:INFO:CONSOLE(0)] "[SUCCESS] reload", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[11198:11198:0509/130302.901828:INFO:CONSOLE(0)] "[FAIL] setNonAutoDiscardable: lastError.message == No tab with id: 5.
Error
    at Object.handleRequest (extensions::binding:64:27)
    at Object.<anonymous> (extensions::binding:374:32)
    at Object.<anonymous> (extensions::test:255:18)
    at Object.handleRequest (extensions::binding:64:27)
    at Object.<anonymous> (extensions::binding:374:32)
    at Object.callback (extensions::test:306:20)
    at safeCallbackApply (extensions::uncaught_exception_handler:27:15)
    at handleResponse (extensions::sendRequest:67:7)", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
[11198:11198:0509/130302.976788:INFO:CONSOLE(0)] "[FAIL] resetAutoDiscardable: FAIL (no message)
Error
    at Object.handleRequest (extensions::binding:64:27)
    at Object.<anonymous> (extensions::binding:374:32)
    at Object.<anonymous> (extensions::test:168:18)
    at Object.handleRequest (extensions::binding:64:27)
    at Object.<anonymous> (extensions::binding:374:32)
    at Object.<anonymous> (extensions::test:156:16)
    at Object.handleRequest (extensions::binding:64:27)
    at Object.<anonymous> (extensions::binding:374:32)
    at resetAutoDiscardable (chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.js:105:5)
    at Object.<anonymous> (extensions::test:110:19)", source: chrome-extension://dgeojcdjgiakejlbkfaglpepbfnkfmgn/discarded.html (0)
../../chrome/browser/extensions/extension_tabs_apitest.cc:277: Failure
Value of: RunExtensionSubtest("tabs/basics", "discarded.html")
  Actual: false
Expected: true
Failed 2 of 5 tests
Stack trace:
    #0 0x0000088e99d7 in StackTraceGetter::CurrentStackTrace(int, int) ./../../third_party/googletest/custom/gtest/internal/custom/stack_trace_getter.cc:22:27
    #1 0x00000891de39 in testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop(int) ./../../third_party/googletest/src/googletest/src/gtest.cc:810:35
    #2 0x00000891c072 in testing::internal::AssertHelper::operator=(testing::Message const&) const ./../../third_party/googletest/src/googletest/src/gtest.cc:386:25
    #3 0x000004f33b8a in ExtensionApiTabTest_OnUpdatedDiscardedState_Test::RunTestOnMainThread() ./../../chrome/browser/extensions/extension_tabs_apitest.cc:277:3
    #4 0x000014a498a0 in content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() ./../../content/public/test/browser_test_base.cc:383:5
    #5 0x0000133782d7 in Run ./../../base/callback.h:125:12
    #6 0x0000133782d7 in ChromeBrowserMainParts::PreMainMessageLoopRunImpl() ./../../chrome/browser/chrome_browser_main.cc:2078:0
    #7 0x000013373ca0 in ChromeBrowserMainParts::PreMainMessageLoopRun() ./../../chrome/browser/chrome_browser_main.cc:1470:18
    #8 0x00000743a995 in chromeos::ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun() ./../../chrome/browser/chromeos/chrome_browser_main_chromeos.cc:715:32
    #9 0x00000bb9a5db in content::BrowserMainLoop::PreMainMessageLoopRun() ./../../content/browser/browser_main_loop.cc:959:13
    #10 0x00000d07bca1 in Run ./../../base/callback.h:125:12
    #11 0x00000d07bca1 in content::StartupTaskRunner::RunAllTasksNow() ./../../content/browser/startup_task_runner.cc:44:0
    #12 0x00000bb92d48 in content::BrowserMainLoop::CreateStartupTasks() ./../../content/browser/browser_main_loop.cc:872:25
    #13 0x00000bba5aa7 in content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&) ./../../content/browser/browser_main_runner.cc:139:17
    #14 0x00000bb87216 in content::BrowserMain(content::MainFunctionParams const&) ./../../content/browser/browser_main.cc:42:32
    #15 0x000012b40273 in content::RunNamedProcessTypeMain(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, content::MainFunctionParams const&, content::ContentMainDelegate*) ./../../content/app/content_main_runner.cc:640:14
    #16 0x000012b4384f in content::ContentMainRunnerImpl::Run() ./../../content/app/content_main_runner.cc:943:12
    #17 0x00001c7e8214 in service_manager::Main(service_manager::MainParams const&) ./../../services/service_manager/embedder/main.cc:452:29
    #18 0x000012b39e68 in content::ContentMain(content::ContentMainParams const&) ./../../content/app/content_main.cc:19:10
    #19 0x000014a47d62 in content::BrowserTestBase::SetUp() ./../../content/public/test/browser_test_base.cc:321:3
[11198:11198:0509/130303.225099:WARNING:pref_notifier_impl.cc(23)] Pref observer found at shutdown.
[11198:11198:0509/130303.283391:WARNING:pref_notifier_impl.cc(23)] Pref observer found at shutdown.
[  FAILED  ] ExtensionApiTabTest.OnUpdatedDiscardedState, where TypeParam =  and GetParam() =  (5804 ms)

Assigning to fdoray@ as he is the expert on the CL in question.
Suspected CL: https://chromium-review.googlesource.com/c/chromium/src/+/1041138

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988

commit c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988
Author: Max Morin <maxmorin@chromium.org>
Date: Fri May 11 08:11:10 2018

Revert "Enforcing freezing a tab prior to proactive discard."

This reverts commit 46c1bd55c8b845db737c1603f3798b2af8f85239.

Reason for revert:  crbug.com/841871 

Original change's description:
> Enforcing freezing a tab prior to proactive discard.
> 
> This CL enforces that a tab is frozen prior to being proactively discarded. This will allow the website to have enough time to persist any state prior to being proactively discarded. Urgent discard behavior is unchanged.
> 
> Bug: 775644
> Change-Id: Ia3ec9e8f53f80d2c940edd065090415cbcdd1f6c
> Reviewed-on: https://chromium-review.googlesource.com/1041138
> Commit-Queue: François Doray <fdoray@chromium.org>
> Reviewed-by: François Doray <fdoray@chromium.org>
> Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#557209}

TBR=fdoray@chromium.org,fmeawad@chromium.org,pavely@chromium.org,varunmohan@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 775644,  841871 
Change-Id: Ia784d8aada40321e14f14133a7a6bb9403d7dda0
Reviewed-on: https://chromium-review.googlesource.com/1054668
Reviewed-by: Max Morin <maxmorin@chromium.org>
Commit-Queue: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557812}
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/lifecycle_state.h
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_lifecycle_unit.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_lifecycle_unit.h
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_lifecycle_unit_source.h
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_lifecycle_unit_source_unittest.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_manager.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_manager_browsertest.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_manager_delegate_chromeos.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/resource_coordinator/tab_manager_unittest.cc
[modify] https://crrev.com/c0426bc1f3e91a2078cdb7fcb7c1adfb25d65988/chrome/browser/sync/sessions/browser_list_router_helper_unittest.cc

Shouldn't happen with latest reland of CL https://chromium-review.googlesource.com/1060290 .