components_unittests failing on chromium.win/Win7 Tests (dbg)(1)

Builders failed on: 
- Win7 Tests (dbg)(1): 
  https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29

Crashed on 2/2 runs since this test was added in r518381. Reverting.

[ RUN      ] CrashKeyStringTest.FormatStackTrace
c:\b\c\win_toolchain\vs_files\a9e1098bba66d2acccc377d5ee81265910f29272\win_sdk\bin\..\..\vc\tools\msvc\14.11.25503\include\xstring(1297) : Assertion failed: cannot seek string iterator before begin
Received fatal exception EXCEPTION_BREAKPOINT
Backtrace:
	base::TestSuite::SuppressErrorDialogs [0x06F180BD+381]
	invalid_parameter [0x7426E551+161]
	std::_String_const_iterator<std::_String_val<std::_Simple_types<char> > >::operator+= [0x024505DA+426]
	std::_String_iterator<std::_String_val<std::_Simple_types<char> > >::operator+= [0x02450405+37]
	std::_String_iterator<std::_String_val<std::_Simple_types<char> > >::operator-= [0x0664771F+31]
	std::_String_iterator<std::_String_val<std::_Simple_types<char> > >::operator- [0x066476A0+80]
	std::basic_string<char,std::char_traits<char>,std::allocator<char> >::back [0x06647601+65]
	crash_reporter::internal::FormatStackTrace [0x066474E1+353]
	base::internal::DstRangeRelationToSrcRangeImpl<unsigned int,unsigned int,base::internal::SaturationDefaultLimits,0,0,1>::Check [0x037F2219+585]
	testing::internal::HandleExceptionsInMethodIfSupported<testing::Test,void> [0x04672499+105]
	testing::Test::Run [0x046723A6+182]
	testing::TestInfo::Run [0x0467305A+250]
	testing::TestCase::Run [0x04673D6B+267]
	testing::internal::UnitTestImpl::RunAllTests [0x0467BE42+786]
	testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl,bool> [0x0467BADE+110]
	testing::UnitTest::Run [0x0467B8D4+324]
	RUN_ALL_TESTS [0x06F17DFF+15]
	base::TestSuite::Run [0x06F17116+150]
	content::UnitTestTestSuite::Run [0x07E44B06+22]
	??$Invoke@ABV?$unique_ptr@VUnitTestTestSuite@content@@U?$default_delete@VUnitTestTestSuite@content@@@std@@@std@@$$V@?$FunctorTraits@P8UnitTestTestSuite@content@@AEHXZX@internal@base@@SAHP8UnitTestTestSuite@content@@AEHXZABV?$unique_ptr@VUnitTestTestSuite@ [0x05BCFCF1+33]
	base::internal::InvokeHelper<0,int>::MakeItSo<int (__thiscall content::UnitTestTestSuite::*const &)(void),std::unique_ptr<content::UnitTestTestSuite,std::default_delete<content::UnitTestTestSuite> > const &> [0x05BCFC0D+77]
	base::internal::Invoker<base::internal::BindState<int (__thiscall content::UnitTestTestSuite::*)(void),std::unique_ptr<content::UnitTestTestSuite,std::default_delete<content::UnitTestTestSuite> > >,int __cdecl(void)>::RunImpl<int (__thiscall content::Unit [0x05BCFB9A+74]
	base::internal::Invoker<base::internal::BindState<int (__thiscall content::UnitTestTestSuite::*)(void),std::unique_ptr<content::UnitTestTestSuite,std::default_delete<content::UnitTestTestSuite> > >,int __cdecl(void)>::Run [0x05BCFA1E+62]
	base::RepeatingCallback<int __cdecl(void)>::Run [0x06F05A92+50]
	base::LaunchUnitTests [0x06F03955+837]
	base::LaunchUnitTests [0x06F036D0+192]
	main [0x0333CF01+129]
	invoke_main [0x097A650E+30] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:78)
	__scrt_common_main_seh [0x097A63B0+336] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283)
	__scrt_common_main [0x097A624D+13] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:326)
	mainCRTStartup [0x097A6588+8] (f:\dd\vctools\crt\vcstartup\src\startup\exe_main.cpp:17)
	BaseThreadInitThunk [0x75DA336A+18]
	RtlInitializeExceptionChain [0x77649902+99]
	RtlInitializeExceptionChain [0x776498D5+54]