1. Sync to ToT (e6adcd2e68a14903eb579399d66a50d8f72564f9) with src-internal.

2. Use the following gn arguments:

enable_mojo_media = true
mojo_media_services = ["cdm"]
mojo_media_host = "utility"
enable_test_mojo_media_client = true
proprietary_codecs = true
ffmpeg_branding = "Chrome"
is_debug = true
use_goma = true
#is_official_build=true
is_chrome_branded=true
is_component_build=true
#enable_nacl = false

3. build browser_tests

4. Run browser_tests

out/GN/browser_tests --gtest_filter=ECKEncryptedMediaTest.InitializeCDMFail

5. Test crash with DCHECK fired:

[7561:7561:1209/163448.256455:FATAL:sequenced_worker_pool.cc(1358)] Check failed: AllPoolsState::USE_WORKER_POOL == g_all_pools_state (1 vs. 0)
#0 0x7f91e0b16c3e base::debug::StackTrace::StackTrace()
#1 0x7f91e0b8406f logging::LogMessage::~LogMessage()
#2 0x7f91e0ceea25 base::SequencedWorkerPool::Inner::FinishStartingAdditionalThread()
#3 0x7f91e0cede53 base::SequencedWorkerPool::Inner::PostTask()
#4 0x7f91e0cf18bd base::SequencedWorkerPool::PostDelayedWorkerTask()
#5 0x7f91e0cf1c35 base::SequencedWorkerPool::PostDelayedTask()
#6 0x7f91e0cb2748 base::TaskRunner::PostTask()
#7 0x00000325a2c6 (anonymous namespace)::PostStoreMetricsClientInfo()
#8 0x00000094185a _ZN4base8internal13FunctorTraitsIPFvRKNS_8CallbackIFvvELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEEvE6InvokeIJS8_EEEvSA_DpOT_
#9 0x000000941808 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKPFvRKNS_8CallbackIFvvELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEEJSA_EEEvOT_DpOT0_
#10 0x000002c8fc76 _ZN4base8internal7InvokerINS0_9BindStateIPFvRKNS_8FilePathEEJEEES6_E7RunImplIRKS7_RKSt5tupleIJEEJEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEES5_
#11 0x00000325bf6c _ZN4base8internal7InvokerINS0_9BindStateIPFvRKN7metrics10ClientInfoEEJEEES7_E3RunEPNS0_13BindStateBaseES6_
#12 0x0000009692b6 base::internal::RunMixin<>::Run()
#13 0x00000427db24 metrics::MetricsStateManager::BackUpCurrentClientInfo()
#14 0x00000427d83e metrics::MetricsStateManager::ForceClientIdCreation()
#15 0x00000427cd8a metrics::MetricsStateManager::MetricsStateManager()
#16 0x00000427e451 metrics::MetricsStateManager::Create()
#17 0x000003259e8c ChromeMetricsServicesManagerClient::GetMetricsStateManager()
#18 0x00000325a0b3 ChromeMetricsServicesManagerClient::CreateEntropyProvider()
#19 0x000006110d0c metrics_services_manager::MetricsServicesManager::CreateEntropyProvider()
#20 0x000003538351 ChromeBrowserMainParts::SetupFieldTrials()
#21 0x00000353b0fb ChromeBrowserMainParts::PreCreateThreadsImpl()
#22 0x000003539b35 ChromeBrowserMainParts::PreCreateThreads()
...