It works for me. My Pixelbook crashes every time I try to reproduce this problem on Chrome OS 69.

This could be a duplicate of Issue 867199, which has been fixed.
The stack from the crash report matches that bug.

	arc::AXTreeSourceArc::SerializeNode(arc::mojom::AccessibilityNodeInfoData*, ui::AXNodeData*) const
0x000059677375c4d3	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/ui/accessibility/ax_tree_serializer.h:521 )	ui::AXTreeSerializer<arc::mojom::AccessibilityNodeInfoData*, ui::AXNodeData, ui::AXTreeData>::SerializeChangedNodes(arc::mojom::AccessibilityNodeInfoData*, ui::AXTreeUpdateBase<ui::AXNodeData, ui::AXTreeData>*)
0x000059677375960a	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/ui/accessibility/ax_tree_serializer.h:397 )	arc::AXTreeSourceArc::NotifyAccessibilityEvent(arc::mojom::AccessibilityEventData*)
0x0000596773755844	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/chrome/browser/chromeos/arc/accessibility/arc_accessibility_helper_bridge.cc:263 )	arc::ArcAccessibilityHelperBridge::OnAccessibilityEvent(mojo::StructPtr<arc::mojom::AccessibilityEventData>)
0x00005967736461bc	(chrome -./gen/components/arc/common/accessibility_helper.mojom.cc:548 )	arc::mojom::AccessibilityHelperHostStubDispatch::Accept(arc::mojom::AccessibilityHelperHost*, mojo::Message*)
0x0000596771e7bbee	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc:423 )	mojo::InterfaceEndpointClient::HandleIncomingMessageThunk::Accept(mojo::Message*)
0x0000596774a79743	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc:306 )	mojo::internal::MultiplexRouter::ProcessIncomingMessage(mojo::internal::MultiplexRouter::MessageWrapper*, mojo::internal::MultiplexRouter::ClientCallBehavior, base::SequencedTaskRunner*)
0x0000596771e7bd81	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/mojo/public/cpp/bindings/lib/multiplex_router.cc:590 )	mojo::internal::MultiplexRouter::Accept(mojo::Message*)
0x0000596771e7b55f	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/mojo/public/cpp/bindings/lib/connector.cc:457 )	mojo::Connector::ReadAllAvailableMessages()
0x0000596771e7c7d2	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/base/callback.h:129 )	mojo::SimpleWatcher::OnHandleReady(int, unsigned int, mojo::HandleSignalsState const&)
0x0000596771e6d4df	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/base/callback.h:99 )	base::MessageLoop::RunTask(base::PendingTask*)
0x0000596771e6dd4d	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/base/message_loop/message_loop.cc:432 )	base::MessageLoop::DoWork()
0x0000596771e78eb6	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/base/message_loop/message_pump_libevent.cc:210 )	base::MessagePumpLibevent::Run(base::MessagePump::Delegate*)
0x00005967749b3c03	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/base/run_loop.cc:102 )	<name omitted>
0x00005967745bfae6	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/chrome/browser/chrome_browser_main.cc:2086 )	ChromeBrowserMainParts::MainMessageLoopRun(int*)
0x0000596772b690ad	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/content/browser/browser_main_loop.cc:1034 )	content::BrowserMainLoop::RunMainMessageLoopParts()
0x0000596772b6c6a1	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/content/browser/browser_main_runner_impl.cc:162 )	content::BrowserMainRunnerImpl::Run()
0x0000596772b6158c	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/content/browser/browser_main.cc:47 )	content::BrowserMain(content::MainFunctionParams const&)
0x00005967745ab3d8	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/content/app/content_main_runner_impl.cc:596 )	content::ContentMainRunnerImpl::Run(bool)
0x00005967745b3112	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/services/service_manager/embedder/main.cc:472 )	service_manager::Main(service_manager::MainParams const&)
0x0000596771f7abd4	(chrome -./../../../../../../../home/chrome-bot/chrome_root/src/content/app/content_main.cc:19 )	ChromeMain
0x00007f15a267d735	(libc-2.23.so -libc-start.c:289 )	__libc_start_main
0x0000596771f6aed8	(chrome + 0x00274ed8 )	_start

I think this is a dupe of the other bug.  Unfortunately the fix never got merged to M69 at the time, so it's not fixed there.  And now we probably won't refresh stable channel on M69 before M70 is promoted, so there's no point to merge now.

I've confirmed on the crash server that M70+ is not affected by crashes with this signature

Thank you, that bug isn't public so I can't see any detail on its scope, symptoms or cause so fingers crossed it's the one impacting me! Even is M70 stable due to push out (specifically for soraka)