also seeing flake on WebRtcBrowserTest.RunsAudioVideoWebRTCCallInTwoTabsEmitsGatheringStateChange

here is an example stack trace:
Indirect leak of 64 byte(s) in 1 object(s) allocated from:
    #0 0x102a0c2 in operator new(unsigned long) /b/swarming/w/ir/kitchen-workdir/src/third_party/llvm/compiler-rt/lib/asan/asan_new_delete.cc:106:3
    #1 0x10e23377 in __libcpp_allocate buildtools/third_party/libc++/trunk/include/new:254:10
    #2 0x10e23377 in allocate buildtools/third_party/libc++/trunk/include/memory:1800
    #3 0x10e23377 in allocate buildtools/third_party/libc++/trunk/include/memory:1549
    #4 0x10e23377 in __construct_node<const std::__1::piecewise_construct_t &, std::__1::tuple<blink::ResourceLoadScheduler::ThrottleOption &&>, std::__1::tuple<> > buildtools/third_party/libc++/trunk/include/__tree:2221
    #5 0x10e23377 in __emplace_unique_key_args<blink::ResourceLoadScheduler::ThrottleOption, const std::__1::piecewise_construct_t &, std::__1::tuple<blink::ResourceLoadScheduler::ThrottleOption &&>, std::__1::tuple<> > buildtools/third_party/libc++/trunk/include/__tree:2167
    #6 0x10e23377 in operator[] buildtools/third_party/libc++/trunk/include/map:1430
    #7 0x10e23377 in blink::ResourceLoadScheduler::GetNextPendingRequest(unsigned long*) third_party/blink/renderer/platform/loader/fetch/resource_load_scheduler.cc:623
    #8 0x10e1f4cf in blink::ResourceLoadScheduler::MaybeRun() third_party/blink/renderer/platform/loader/fetch/resource_load_scheduler.cc:667:10
    #9 0x2129b09d in LoosenLoadThrottlingPolicy third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h:173:51
    #10 0x2129b09d in blink::Document::WillInsertBody() third_party/blink/renderer/core/dom/document.cc:3317
    #11 0x222b1816 in blink::HTMLConstructionSite::InsertHTMLBodyElement(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_construction_site.cc:685:16
    #12 0x22205a92 in blink::HTMLTreeBuilder::ProcessStartTag(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_tree_builder.cc:1038:15
    #13 0x22234edc in blink::HTMLTreeBuilder::DefaultForAfterHead() third_party/blink/renderer/core/html/parser/html_tree_builder.cc:2485:3
    #14 0x22214b82 in blink::HTMLTreeBuilder::ProcessEndOfFile(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_tree_builder.cc:2370:7
    #15 0x221f6a4a in blink::HTMLTreeBuilder::ProcessToken(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_tree_builder.cc:365:7
    #16 0x221ee6ac in blink::HTMLTreeBuilder::ConstructTree(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_tree_builder.cc:313:5
    #17 0x2210520a in blink::HTMLDocumentParser::ConstructTreeFromHTMLToken() third_party/blink/renderer/core/html/parser/html_document_parser.cc:718:18
    #18 0x220f86f4 in blink::HTMLDocumentParser::PumpTokenizer() third_party/blink/renderer/core/html/parser/html_document_parser.cc:671:5
    #19 0x220f7077 in PumpTokenizerIfPossible third_party/blink/renderer/core/html/parser/html_document_parser.cc:251:3
    #20 0x220f7077 in blink::HTMLDocumentParser::PrepareToStopParsing() third_party/blink/renderer/core/html/parser/html_document_parser.cc:222
    #21 0x2210d63e in AttemptToEnd third_party/blink/renderer/core/html/parser/html_document_parser.cc:918:3
    #22 0x2210d63e in blink::HTMLDocumentParser::Finish() third_party/blink/renderer/core/html/parser/html_document_parser.cc:968
    #23 0x23408d74 in blink::DocumentLoader::FinishedLoading(base::TimeTicks) third_party/blink/renderer/core/loader/document_loader.cc:503:16
    #24 0x234117b0 in blink::DocumentLoader::MaybeLoadEmpty() third_party/blink/renderer/core/loader/document_loader.cc:918:3
    #25 0x23411b7c in blink::DocumentLoader::StartLoading() third_party/blink/renderer/core/loader/document_loader.cc:928:7
    #26 0x234409b1 in blink::FrameLoader::Init() third_party/blink/renderer/core/loader/frame_loader.cc:241:33
    #27 0x21d9feaf in blink::LocalFrame::Init() third_party/blink/renderer/core/frame/local_frame.cc:176:11
    #28 0x21f39948 in blink::WebLocalFrameImpl::InitializeCoreFrame(blink::Page&, blink::FrameOwner*, WTF::AtomicString const&) third_party/blink/renderer/core/frame/web_local_frame_impl.cc:1806:11
    #29 0x21f3ce9a in blink::WebLocalFrameImpl::CreateChildFrame(WTF::AtomicString const&, blink::HTMLFrameOwnerElement*) third_party/blink/renderer/core/frame/web_local_frame_impl.cc:1852:19
    #30 0x224ed5ac in blink::HTMLFrameOwnerElement::LoadOrRedirectSubframe(blink::KURL const&, WTF::AtomicString const&, bool) third_party/blink/renderer/core/html/html_frame_owner_element.cc:383:43
    #31 0x225982d0 in blink::HTMLFrameElementBase::OpenURL(bool) third_party/blink/renderer/core/html/html_frame_element_base.cc:112:8
    #32 0x2259aa71 in blink::HTMLFrameElementBase::SetNameAndOpenURL() third_party/blink/renderer/core/html/html_frame_element_base.cc:188:3
    #33 0x212263e3 in blink::ContainerNode::NotifyNodeInserted(blink::Node&, blink::ContainerNode::ChildrenChangeSource) third_party/blink/renderer/core/dom/container_node.cc:918:20
    #34 0x2121c836 in blink::ContainerNode::ParserAppendChild(blink::Node*) third_party/blink/renderer/core/dom/container_node.cc:894:3
    #35 0x222b7ee2 in blink::Insert(blink::HTMLConstructionSiteTask&) third_party/blink/renderer/core/html/parser/html_construction_site.cc:119:18
    #36 0x2229dc95 in ExecuteInsertTask third_party/blink/renderer/core/html/parser/html_construction_site.cc:125:3
    #37 0x2229dc95 in blink::HTMLConstructionSite::ExecuteTask(blink::HTMLConstructionSiteTask&) third_party/blink/renderer/core/html/parser/html_construction_site.cc:179
    #38 0x222a3668 in blink::HTMLConstructionSite::ExecuteQueuedTasks() third_party/blink/renderer/core/html/parser/html_construction_site.cc:335:5
    #39 0x221ee85d in blink::HTMLTreeBuilder::ConstructTree(blink::AtomicHTMLToken*) third_party/blink/renderer/core/html/parser/html_tree_builder.cc:331:9

additional flake seen in:
WebRtcBrowserTest.RunsAudioVideoWebRTCCallInTwoTabsVP8
WebRtcDisableEncryptionFlagBrowserTest.VerifyEncryption

probably others are flaking as well.