Findit identified the culprit r575974 with confidence 70.0% in the config "chromium.chromiumos / linux-chromeos-dbg"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVypwELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJxY2hyb21pdW0uY2hyb21pdW1vcy9saW51eC1jaHJvbWVvcy1kYmcvNzAzOC9jb250ZW50X2Jyb3dzZXJ0ZXN0cy9VR0Y1YldWdWRFRndjRUp5YjNkelpYSlVaWE4wTGtOaGJrMWhhMlZRWVhsdFpXNTAMCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

If the culprit above is wrong, please file a bug using this link and hit submit:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Analyzer%20-%20Wrong%20result%20for%20PaymentAppBrowserTest.CanMakePayment&comment=Link%20to%20Analysis%3A%20https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVypwELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJxY2hyb21pdW0uY2hyb21pdW1vcy9saW51eC1jaHJvbWVvcy1kYmcvNzAzOC9jb250ZW50X2Jyb3dzZXJ0ZXN0cy9VR0Y1YldWdWRFRndjRUp5YjNkelpYSlVaWE4wTGtOaGJrMWhhMlZRWVhsdFpXNTAMCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

Hi Ganggui, can you take a look please?  Seems there could be a problem with memoty allocation in blink::PaymentInstrument.  The call stack for the failed test is:

[ RUN      ] PaymentAppBrowserTest.CanMakePayment
[20909:20916:0729/000031.145251:ERROR:network_service.cc(66)] Not implemented reached in std::unique_ptr<net::NetworkChangeNotifier> network::(anonymous namespace)::CreateNetworkChangeNotifierIfNeeded()

DevTools listening on ws://127.0.0.1:35451/devtools/browser/9d8f5219-19ed-4b76-a8e6-d55ac586feb3
[20909:20909:0729/000031.166746:ERROR:proxy_resolution_service.cc(1528)] ProxyConfigService for ChromeOS should be created in profile_io_data.cc::CreateProxyConfigService and this should be used only for examples.
[1:1:0729/000032.096669:FATAL:heap_page.h(989)] Check failed: IsMarked(). 
#0 0x7f51d24a007d base::debug::StackTrace::StackTrace()
#1 0x7f51d21b5c8c base::debug::StackTrace::StackTrace()
#2 0x7f51d221f68d logging::LogMessage::~LogMessage()
#3 0x7f51c16b6e1d blink::HeapObjectHeader::Unmark()
#4 0x7f51c16b26a6 blink::NormalPageArena::PromptlyFreeObjectInFreeList()
#5 0x7f51c16b24ca blink::NormalPageArena::PromptlyFreeObject()
#6 0x7f51c16a5dc9 blink::HeapAllocator::BackingFree()
#7 0x7f51c16a5df5 blink::HeapAllocator::FreeVectorBacking()
#8 0x7f51be27334c WTF::VectorBuffer<>::DeallocateBuffer()
#9 0x7f51be2732dc WTF::VectorBuffer<>::Destruct()
#10 0x7f51be399295 WTF::Vector<>::~Vector()
#11 0x7f51be399065 blink::HeapVector<>::~HeapVector()
#12 0x7f51be978921 blink::PaymentInstrument::~PaymentInstrument()
#13 0x7f51bee5f2e5 std::__1::__tuple_leaf<>::~__tuple_leaf()
...