A separate CL caused a massive number of errors on the Valgrind bot here: https://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%284%29/builds/37388 but hidden inside is https://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%284%29/builds/37388/steps/memory%20test%3A%20unit/logs/672012F84C9C713F

Leak_DefinitelyLost
2,603 (72 direct, 2,531 indirect) bytes in 1 blocks are definitely lost in loss record 14,414 of 14,697
operator new(unsigned long) (m_replacemalloc/vg_replace_malloc.c:1140)
TestingProfile::CreateRequestContext(...) (chrome/test/base/testing_profile.cc:816)
ChromeContentBrowserClient::CreateRequestContext(...) (content/browser/storage_partition_impl_map.cc:465)
content::(anonymous namespace)::GetStoragePartitionFromConfig(...) (content/browser/browser_context.cc:208)
(anonymous namespace)::LogHostedAppUnlimitedStorageUsage(scoped_refptr<extensions::Extension const>, content::BrowserContext*) (chrome/browser/extensions/extension_special_storage_policy.cc:64)
ExtensionSpecialStoragePolicy::GrantRightsForExtension(extensions::Extension const*, content::BrowserContext*) (chrome/browser/extensions/extension_special_storage_policy.cc:190)
ExtensionService::NotifyExtensionLoaded(extensions::Extension const*) (chrome/browser/extensions/extension_service.cc:1065)
ExtensionService::AddExtension(extensions::Extension const*) (chrome/browser/extensions/extension_service.cc:1521)
ExtensionService::FinishInstallation(extensions::Extension const*) (chrome/browser/extensions/extension_service.cc:1938)
ExtensionService::AddNewOrUpdatedExtension(extensions::Extension const*, extensions::Extension::State, int, syncer::Ordinal<syncer::StringOrdinalTraits> const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (chrome/browser/extensions/extension_service.cc:1867)
ExtensionService::OnExtensionInstalled(extensions::Extension const*, syncer::Ordinal<syncer::StringOrdinalTraits> const&, int) (chrome/browser/extensions/extension_service.cc:1816)
extensions::CrxInstaller::ReportSuccessFromUIThread() (chrome/browser/extensions/crx_installer.cc:829)
Suppression (error hash=#672012F84C9C713F#):
For more info on using suppressions see http://dev.chromium.org/developers/tree-sheriffs/sheriff-details-chromium/memory-sheriff#TOC-Suppressing-memory-reports
{
<insert_a_suppression_name_here>
Memcheck:Leak
fun:_Znw*
fun:_ZN14TestingProfile20CreateRequestContextEPSt3mapISs10linked_ptrIN3net20URLRequestJobFactory15ProtocolHandlerEESt4lessISsESaISt4pairIKSsS5_EEE12ScopedVectorINS2_21URLRequestInterceptorEE
fun:_ZN26ChromeContentBrowserClient20CreateRequestContextEPN7content14BrowserContextEPSt3mapISs10linked_ptrIN3net20URLRequestJobFactory15ProtocolHandlerEESt4lessISsESaISt4pairIKSsS8_EEE12ScopedVectorINS5_21URLRequestInterceptorEE
fun:_ZN7content23StoragePartitionImplMap3GetERKSsS2_b
fun:_ZN7content12_GLOBAL__N_129GetStoragePartitionFromConfigEPNS_14BrowserContextERKSsS4_b
fun:_ZN7content14BrowserContext26GetStoragePartitionForSiteEPS0_RK4GURL
fun:_ZN12_GLOBAL__N_133LogHostedAppUnlimitedStorageUsageE13scoped_refptrIKN10extensions9ExtensionEEPN7content14BrowserContextE
fun:_ZN29ExtensionSpecialStoragePolicy23GrantRightsForExtensionEPKN10extensions9ExtensionEPN7content14BrowserContextE
fun:_ZN16ExtensionService21NotifyExtensionLoadedEPKN10extensions9ExtensionE
fun:_ZN16ExtensionService12AddExtensionEPKN10extensions9ExtensionE
fun:_ZN16ExtensionService18FinishInstallationEPKN10extensions9ExtensionE
fun:_ZN16ExtensionService24AddNewOrUpdatedExtensionEPKN10extensions9ExtensionENS1_5StateEiRKN6syncer7OrdinalINS5_19StringOrdinalTraitsEEERKSs
fun:_ZN16ExtensionService20OnExtensionInstalledEPKN10extensions9ExtensionERKN6syncer7OrdinalINS4_19StringOrdinalTraitsEEEi
fun:_ZN10extensions12CrxInstaller25ReportSuccessFromUIThreadEv
}

I believe this is due to https://chromium.googlesource.com/chromium/src/+/a8bee310d105d8167d39a9d4d496ba49c823576d, please take a look. Same leak happens on Linux Valgrind too: https://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20Tests%20%28valgrind%29%285%29/builds/40584