Could you please go to chrome://crashes and send the crash ids to us? If crash reporting is not enabled, please enable it.

Uploaded Crash Report ID 066660ea6d7dd9c0

Thread 0 (id: 7128) CRASHED [EXCEPTION_ACCESS_VIOLATION_READ @ 0x000000d8 ] MAGIC SIGNATURE THREAD
Stack Quality100%Show frame trust levels
0x00007ffd19edb7f1	(chrome.dll -render_frame_devtools_agent_host.cc:1198 )	content::RenderFrameDevToolsAgentHost::GetOpenerId()
0x00007ffd19ed33a9	(chrome.dll -target_handler.cc:26 )	content::protocol::`anonymous namespace'::CreateInfo
0x00007ffd19ed38ef	(chrome.dll -target_handler.cc:332 )	content::protocol::TargetHandler::DevToolsAgentHostCreated(content::DevToolsAgentHost *)
0x00007ffd196c0dea	(chrome.dll -devtools_agent_host_impl.cc:317 )	content::DevToolsAgentHost::AddObserver(content::DevToolsAgentHostObserver *)
0x00007ffd19ed2c22	(chrome.dll -target_handler.cc:196 )	content::protocol::TargetHandler::SetDiscoverTargets(bool)
0x00007ffd19df34d6	(chrome.dll -target.cc:838 )	content::protocol::Target::DispatcherImpl::setDiscoverTargets(int,std::unique_ptr<content::protocol::DictionaryValue,std::default_delete<content::protocol::DictionaryValue> >,content::protocol::ErrorSupport *)
0x00007ffd19dcc016	(chrome.dll -emulation.cc:224 )	content::protocol::Emulation::DispatcherImpl::dispatch(int,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,std::unique_ptr<content::protocol::DictionaryValue,std::default_delete<content::protocol::DictionaryValue> >)
0x00007ffd19de65ef	(chrome.dll -protocol.cc:822 )	content::protocol::UberDispatcher::dispatch(std::unique_ptr<content::protocol::Value,std::default_delete<content::protocol::Value> >,int *,std::basic_string<char,std::char_traits<char>,std::allocator<char> > *)
0x00007ffd19eace61	(chrome.dll -devtools_session.cc:152 )	content::DevToolsSession::Dispatch(std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,int *,std::basic_string<char,std::char_traits<char>,std::allocator<char> > *)
0x00007ffd19eda3c1	(chrome.dll -render_frame_devtools_agent_host.cc:644 )	content::RenderFrameDevToolsAgentHost::DispatchProtocolMessage(content::DevToolsSession *,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &)
0x00007ffd19ea231a	(chrome.dll -devtools_agent_host_impl.cc:177 )	content::DevToolsAgentHostImpl::DispatchProtocolMessage(content::DevToolsAgentHostClient *,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &)
0x00007ffd1b05e922	(chrome.dll -devtools_ui_bindings.cc:1074 )	DevToolsUIBindings::DispatchProtocolMessageFromDevToolsFrontend(std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &)
0x00007ffd1b06b320	(chrome.dll -devtools_embedder_message_dispatcher.cc:91 )	`anonymous namespace'::ParseAndHandle<const std::basic_string<char,std::char_traits<char>,std::allocator<char> > &>
0x00007ffd1b06af9e	(chrome.dll -devtools_embedder_message_dispatcher.cc:123 )	DispatcherImpl::Dispatch(base::RepeatingCallback<void > const &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,base::ListValue const *)
0x00007ffd1b05bb72	(chrome.dll -devtools_ui_bindings.cc:627 )	DevToolsUIBindings::HandleMessageFromDevToolsFrontend(std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &)
0x00007ffd19c70beb	(chrome.dll -devtools.mojom.cc:383 )	content::mojom::DevToolsFrontendHostStubDispatch::Accept(content::mojom::DevToolsFrontendHost *,mojo::Message *)
0x00007ffd1a5a5632	(chrome.dll -ipc_mojo_bootstrap.cc:789 )	IPC::`anonymous namespace'::ChannelAssociatedGroupController::AcceptOnProxyThread
0x00007ffd1a5a3db6	(chrome.dll -bind_internal.h:333 )	base::internal::Invoker<base::internal::BindState<void (IPC::(anonymous namespace)::ChannelAssociatedGroupController::*)(mojo::Message),scoped_refptr<IPC::(anonymous namespace)::ChannelAssociatedGroupController>,base::internal::PassedWrapper<mojo::Message> >,void ()>::Run
0x00007ffd19561556	(chrome.dll -task_annotator.cc:53 )	base::debug::TaskAnnotator::RunTask(char const *,base::PendingTask *)
0x00007ffd19560e3b	(chrome.dll -message_loop.cc:391 )	base::MessageLoop::RunTask(base::PendingTask *)
0x00007ffd19560756	(chrome.dll -message_loop.cc:454 )	base::MessageLoop::DoWork()
0x00007ffd1967b66c	(chrome.dll -message_pump_win.cc:173 )	base::MessagePumpForUI::DoRunLoop()
0x00007ffd195712e4	(chrome.dll -message_pump_win.cc:56 )	base::MessagePumpWin::Run(base::MessagePump::Delegate *)
0x00007ffd19560123	(chrome.dll -run_loop.cc:114 )	base::RunLoop::Run()
0x00007ffd1995aadf	(chrome.dll -chrome_browser_main.cc:1939 )	ChromeBrowserMainParts::MainMessageLoopRun(int *)
0x00007ffd1995a8d6	(chrome.dll -browser_main_loop.cc:1196 )	content::BrowserMainLoop::RunMainMessageLoopParts()
0x00007ffd1995a884	(chrome.dll -browser_main_runner.cc:140 )	content::BrowserMainRunnerImpl::Run()
0x00007ffd1955897c	(chrome.dll -browser_main.cc:46 )	content::BrowserMain(content::MainFunctionParams const &)
0x00007ffd19558809	(chrome.dll -content_main_runner.cc:427 )	content::RunNamedProcessTypeMain(std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,content::MainFunctionParams const &,content::ContentMainDelegate *)
0x00007ffd195586b9	(chrome.dll -content_main_runner.cc:705 )	content::ContentMainRunnerImpl::Run()
0x00007ffd195457e9	(chrome.dll -main.cc:456 )	service_manager::Main(service_manager::MainParams const &)
0x00007ffd1954537f	(chrome.dll -content_main.cc:19 )	content::ContentMain(content::ContentMainParams const &)
0x00007ffd19541b50	(chrome.dll -chrome_main.cc:130 )	ChromeMain
0x00007ff734cc34c9	(chrome.exe -main_dll_loader_win.cc:199 )	MainDllLoader::Launch(HINSTANCE__ *,base::TimeTicks)
0x00007ff734cc169c	(chrome.exe -chrome_exe_main_win.cc:230 )	wWinMain
0x00007ff734d9bc62	(chrome.exe -exe_common.inl:283 )	__scrt_common_main_seh
0x00007ffd771e1fe3	(KERNEL32.DLL + 0x00011fe3 )	BaseThreadInitThunk
0x00007ffd7794ef90	(ntdll.dll + 0x0006ef90 )	RtlUserThreadStart

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fe6b1c49b76daca6c4c14a94cb8b545834052d94

commit fe6b1c49b76daca6c4c14a94cb8b545834052d94
Author: Pavel Feldman <pfeldman@chromium.org>
Date: Sat Dec 16 02:19:01 2017

DevTools: don't retain inspected agent_host while reloading front-end.

This change also does not force extension popup close upon inspect session
termination.

Bug:  795403 
Change-Id: I9ab3e8f0f6b5360f1475f302ab34d18b5b53939f
Reviewed-on: https://chromium-review.googlesource.com/830983
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524563}
[modify] https://crrev.com/fe6b1c49b76daca6c4c14a94cb8b545834052d94/chrome/browser/devtools/devtools_ui_bindings.cc
[modify] https://crrev.com/fe6b1c49b76daca6c4c14a94cb8b545834052d94/chrome/browser/ui/views/extensions/extension_popup.cc
[modify] https://crrev.com/fe6b1c49b76daca6c4c14a94cb8b545834052d94/content/browser/devtools/render_frame_devtools_agent_host.cc

Verified the fix on Windows 10 using Chrome dev version #65.0.3298.0 with steps mentioned in comment #0.
Attaching screen cast for reference.
No crash is seen on changing theme of inspected devtools. Hence, the fix is working as expected.
Adding the verified labels.

[Auto-generated comment by a script] We noticed that this issue is targeted for M-64; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-64 label, otherwise remove Merge-TBD label. Thanks.

This will need to be merged to M64. Can you please confirm if this is a safe merge and well tested in canary/dev?

friendly ping on this. 

Confirmed with pfeldman@ not a blocker, edge case, and we'll fix it for 65.