An example stack trace where FeatureList is not initialized (running media_blink_unittests):

* thread #1: tid = 0x3c22c0c, 0x000000010057c6c2 media_blink_unittests`base::FeatureList::IsFeatureEnabled(this=0x0000000000000000, feature=0x00000001081fcf10) + 82 at feature_list.cc:173, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x78)
  * frame #0: 0x000000010057c6c2 media_blink_unittests`base::FeatureList::IsFeatureEnabled(this=0x0000000000000000, feature=0x00000001081fcf10) + 82 at feature_list.cc:173
    frame #1: 0x000000010057c5fb media_blink_unittests`base::FeatureList::IsEnabled(feature=0x00000001081fcf10) + 43 at feature_list.cc:131
    frame #2: 0x0000000100dff9bf media_blink_unittests`gin::IsolateHolder::Initialize(mode=kNonStrictMode, v8_extras_mode=kStableV8Extras, allocator=0x0000000110d03630) + 223 at isolate_holder.cc:91
    frame #3: 0x0000000105af3f72 media_blink_unittests`blink::V8Initializer::initializeMainThread() + 354 at V8Initializer.cpp:368
    frame #4: 0x00000001031a1aee media_blink_unittests`blink::initialize(platform=0x0000000110f1a610) + 62 at WebKit.cpp:87
    frame #5: 0x000000010014f118 media_blink_unittests`BlinkMediaTestSuite::Initialize(this=0x00007fff5fbffab8) + 488 at run_all_unittests.cc:132
    frame #6: 0x00000001008527aa media_blink_unittests`base::TestSuite::Run(this=0x00007fff5fbffab8) + 74 at test_suite.cc:215
    frame #7: 0x0000000100152ae7 media_blink_unittests`int base::internal::RunnableAdapter<int (base::TestSuite::*)()>::Run<>(this=0x00007fff5fbff3b8, object=0x00007fff5fbffab8) + 119 at bind_internal.h:181
    frame #8: 0x00000001001529f0 media_blink_unittests`int base::internal::InvokeHelper<false, int, base::internal::RunnableAdapter<int (base::TestSuite::*)()> >::MakeItSo<BlinkMediaTestSuite*>(runnable=(method_ = 0x0000000100852760), args=0x00007fff5fbff410)()>, BlinkMediaTestSuite*&&) + 64 at bind_internal.h:303
    frame #9: 0x0000000100152983 media_blink_unittests`base::internal::Invoker<base::IndexSequence<0ul>, base::internal::BindState<base::internal::RunnableAdapter<int (base::TestSuite::*)()>, int (base::TestSuite*), base::internal::UnretainedWrapper<BlinkMediaTestSuite> >, base::internal::InvokeHelper<false, int, base::internal::RunnableAdapter<int (base::TestSuite::*)()> >, int ()>::Run(base=0x0000000110f1d1d0) + 115 at bind_internal.h:362
    frame #10: 0x000000010084413f media_blink_unittests`base::Callback<int (), (base::internal::CopyMode)1>::Run(this=0x00007fff5fbffaa8) const + 63 at callback.h:397
    frame #11: 0x0000000100841587 media_blink_unittests`base::(anonymous namespace)::LaunchUnitTestsInternal(run_test_suite=0x00007fff5fbffaa8, default_jobs=24, default_batch_limit=10, use_job_objects=true, gtest_init=0x00007fff5fbffa08), (base::internal::CopyMode)1> const&, int, int, bool, base::Callback<void (), (base::internal::CopyMode)1> const&) + 375 at unit_test_launcher.cc:206
    frame #12: 0x00000001008413da media_blink_unittests`base::LaunchUnitTests(argc=3, argv=0x00007fff5fbffb20, run_test_suite=0x00007fff5fbffaa8), (base::internal::CopyMode)1> const&) + 122 at unit_test_launcher.cc:445
    frame #13: 0x000000010014f31f media_blink_unittests`main(argc=3, argv=0x00007fff5fbffb20) + 223 at run_all_unittests.cc:138
    frame #14: 0x0000000100001e64 media_blink_unittests`start + 52

So the issue in the above trace is that base::TestSuite::Run() doesn't get to the part where it creates FeatureList yet. So this should be fairly straight forward to fix. Not sure if other cases are similar or not.

The following tests use different harness (content::UnitTestTestSuite::UnitTestTestSuite()): 
app_shell_unittests, content_unittests, extensions_unittests, content_gl_tests and unit_tests.

browser_tests uses something else.

In addition, gin_shell does not initialize FeatureList which causes gin_unittests failures.

The browser tests failure looks like a PPAPI plugin process issue. Here's a stack trace:

0   Chromium Framework                  0x000000010e812e0f _ZN4base5debug10StackTraceC2Ev + 47
1   Chromium Framework                  0x000000010e812fb3 _ZN4base5debug10StackTraceC1Ev + 35
2   Chromium Framework                  0x000000010e812d67 _ZN4base5debug12_GLOBAL__N_122StackDumpSignalHandlerEiP9__siginfoPv + 1255
3   libsystem_platform.dylib            0x00007fff8a97e52a _sigtramp + 26
4   ???                                 0x00007fff532c0510 0x0 + 140734588781840
5   Chromium Framework                  0x000000010e81d26b _ZN4base11FeatureList9IsEnabledERKNS_7FeatureE + 43
6   Chromium Framework                  0x0000000116d5e2ef _ZN3gin13IsolateHolder10InitializeENS0_10ScriptModeENS0_12V8ExtrasModeEPN2v811ArrayBuffer9AllocatorE + 223
7   Chromium Framework                  0x000000010e73e5f9 _ZN10chrome_pdf12_GLOBAL__N_17SetUpV8Ev + 41
8   Chromium Framework                  0x000000010e73e56b _ZN10chrome_pdf13InitializeSDKEv + 27
9   Chromium Framework                  0x000000010e73aa9d _ZN10chrome_pdf9PDFModule14CreateInstanceEi + 125
10  Chromium Framework                  0x000000011f465117 _ZN2pp18Instance_DidCreateEijPPKcS2_ + 87
11  Chromium Framework                  0x0000000116ed6716 _ZN5ppapi17CallWhileUnlockedI7PP_BoolijPPKcS4_ijS4_S4_EET_PFS5_T0_T1_T2_T3_ERKT4_RKT5_RKT6_RKT7_ + 86
12  Chromium Framework                  0x0000000116ed6691 _ZN5ppapi21PPP_Instance_Combined9DidCreateEijPPKcS3_ + 81
13  Chromium Framework                  0x000000011f0d4b60 _ZN5ppapi5proxy18PPP_Instance_Proxy20OnPluginMsgDidCreateEiRKNSt3__16vectorINS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEENS7_IS9_EEEESD_P7PP_Bool + 2160
14  Chromium Framework                  0x000000011f0d7ac3 _ZN4base20DispatchToMethodImplIPN5ppapi5proxy18PPP_Instance_ProxyEMS3_FviRKNSt3__16vectorINS5_12basic_stringIcNS5_11char_traitsIcEENS5_9allocatorIcEEEENSA_ISC_EEEESG_P7PP_BoolEJiSE_SE_EJSH_EJLm0ELm1ELm2EEJLm0EEEEvRKT_T0_RKNS5_5tupleIJDpT1_EEEPNSP_IJDpT2_EEENS_13IndexSequenceIJXspT3_EEEENSZ_IJXspT4_EEEE + 339
15  Chromium Framework                  0x000000011f0d77c6 _ZN4base16DispatchToMethodIPN5ppapi5proxy18PPP_Instance_ProxyEMS3_FviRKNSt3__16vectorINS5_12basic_stringIcNS5_11char_traitsIcEENS5_9allocatorIcEEEENSA_ISC_EEEESG_P7PP_BoolEJiSE_SE_EJSH_EEEvRKT_T0_RKNS5_5tupleIJDpT1_EEEPNSP_IJDpT2_EEE + 102
16  Chromium Framework                  0x000000011f0d41b2 _ZN3IPC8MessageTI35PpapiMsg_PPPInstance_DidCreate_MetaNSt3__15tupleIJiNS2_6vectorINS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEENS8_ISA_EEEESC_EEENS3_IJ7PP_BoolEEEE8DispatchIN5ppapi5proxy18PPP_Instance_ProxyESK_vMSK_FviRKSC_SM_PSE_EEEbPKNS_7MessageEPT_PT0_PT1_T2_ + 1058
17  Chromium Framework                  0x000000011f0d39fe _ZN5ppapi5proxy18PPP_Instance_Proxy17OnMessageReceivedERKN3IPC7MessageE + 430
18  Chromium Framework                  0x000000011ef9d861 _ZN5ppapi5proxy10Dispatcher17OnMessageReceivedERKN3IPC7MessageE + 305
19  Chromium Framework                  0x000000011f031d22 _ZN5ppapi5proxy16PluginDispatcher17OnMessageReceivedERKN3IPC7MessageE + 1010
20  Chromium Framework                  0x0000000111045da6 _ZN3IPC12ChannelProxy7Context17OnDispatchMessageERKNS_7MessageE + 166
21  Chromium Framework                  0x000000011104c665 _ZN4base8internal15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEE3RunIS4_JS7_EEEvRK13scoped_refptrIT_EDpOT0_ + 149
22  Chromium Framework                  0x000000011104c52a _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEEEE8MakeItSoIJRK13scoped_refptrIS5_ES8_EEEvSB_DpOT_ + 74
23  Chromium Framework                  0x000000011104c4bc _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0ELm1EEEENS0_9BindStateINS0_15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS6_7MessageEEEEFvPS8_SB_EJSF_SB_EEENS0_12InvokeHelperILb0EvSE_EEFvvEE3RunEPNS0_13BindStateBaseE + 140
24  Chromium Framework                  0x00000001121215bf _ZNK4base8CallbackIFvvELNS_8internal8CopyModeE1EE3RunEv + 63
25  Chromium Framework                  0x000000010e81464e _ZN4base5debug13TaskAnnotator7RunTaskEPKcRKNS_11PendingTaskE + 654
26  Chromium Framework                  0x000000010e8d0460 _ZN4base11MessageLoop7RunTaskERKNS_11PendingTaskE + 848
27  Chromium Framework                  0x000000010e8d0a96 _ZN4base11MessageLoop21DeferOrRunPendingTaskERKNS_11PendingTaskE + 86
28  Chromium Framework                  0x000000010e8d1148 _ZN4base11MessageLoop6DoWorkEv + 552
29  Chromium Framework                  0x000000010e7d56b8 _ZN4base24MessagePumpCFRunLoopBase7RunWorkEv + 104
30  Chromium Framework                  0x000000010e7d562a ___ZN4base24MessagePumpCFRunLoopBase13RunWorkSourceEPv_block_invoke + 42
31  Chromium Framework                  0x000000010e895c8a _ZN4base3mac15CallWithEHFrameEU13block_pointerFvvE + 10
32  Chromium Framework                  0x000000010e7d49c5 _ZN4base24MessagePumpCFRunLoopBase13RunWorkSourceEPv + 101
33  CoreFoundation                      0x00007fff9a51b8b1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
34  CoreFoundation                      0x00007fff9a4fb0ac __CFRunLoopDoSources0 + 556
35  CoreFoundation                      0x00007fff9a4fa5cf __CFRunLoopRun + 927
36  CoreFoundation                      0x00007fff9a4f9fc8 CFRunLoopRunSpecific + 296
37  Chromium Framework                  0x000000010e7d5fdc _ZN4base20MessagePumpCFRunLoop5DoRunEPNS_11MessagePump8DelegateE + 76
38  Chromium Framework                  0x000000010e7d52cd _ZN4base24MessagePumpCFRunLoopBase3RunEPNS_11MessagePump8DelegateE + 125
39  Chromium Framework                  0x000000010e8cfcaa _ZN4base11MessageLoop10RunHandlerEv + 298
40  Chromium Framework                  0x000000010e967205 _ZN4base7RunLoop3RunEv + 85
41  Chromium Framework                  0x000000010e8cd79f _ZN4base11MessageLoop3RunEv + 303
42  Chromium Framework                  0x000000010e6d83c3 _ZN7content15PpapiPluginMainERKNS_18MainFunctionParamsE + 2931
43  Chromium Framework                  0x000000010e6f7527 _ZN7content23RunNamedProcessTypeMainERKNSt3__112basic_stringIcNS0_11char_traitsIcEENS0_9allocatorIcEEEERKNS_18MainFunctionParamsEPNS_19ContentMainDelegateE + 599
44  Chromium Framework                  0x000000010e6f91d2 _ZN7content21ContentMainRunnerImpl3RunEv + 626
45  Chromium Framework                  0x000000010e6f6d3d _ZN7content11ContentMainERKNS_17ContentMainParamsE + 349
46  Chromium Framework                  0x000000010cba3d13 ChromeMain + 83
47  Chromium Helper                     0x000000010c93bd6f main + 783
48  Chromium Helper                     0x000000010c93ba54 start + 52
49  ???                                 0x0000000000000009 0x0 + 9
asvitkine-macpro2:src asvitkine$ 

Okay, quite a few things needed to be updated for this, but here's a CL that passes trybots with a feature in gin/ : https://codereview.chromium.org/1848523002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e6be55d0de165a41e25a5bd4d41181f562caf3f3

commit e6be55d0de165a41e25a5bd4d41181f562caf3f3
Author: asvitkine <asvitkine@chromium.org>
Date: Mon Apr 04 23:29:50 2016

Changes to support using base/feature_list.h from gin/.

Since gin/ (V8) is used from a number of different processes and
test harnesses, this required updating them to ensure they initialize
a base::FeatureList instance (which is required before querying the
API to ensure code doesn't incorrectly query the API too early).

Additionally, for test_suite.cc, the FeatureList initialization needed
to happen earlier - since some sub-classes of it initialize gin from
their Initialize() functions. The initialization was also switched to
use FeatureList::InitializeInstance() since for some test suites,
a FeatureList would already exist.

BUG= 599165 , 563705 

Review URL: https://codereview.chromium.org/1848523002

Cr-Commit-Position: refs/heads/master@{#385053}

[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/base/feature_list.cc
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/base/feature_list.h
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/base/test/test_suite.cc
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/base/test/test_suite.h
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/content/ppapi_plugin/ppapi_plugin_main.cc
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/content/test/test_blink_web_unit_test_support.cc
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/content/utility/utility_main.cc
[modify] https://crrev.com/e6be55d0de165a41e25a5bd4d41181f562caf3f3/gin/shell/gin_main.cc