Chrome Version: Commit in backing tree 4f56da4755ccc370cd682cce472d4ba1c0781207 (== p438529 landed 12/14)
OS: Mac OS X El Capitan 10.11.6 (though I don't believe that's relevant)

What steps will reproduce the problem?
(1) Build Chromium at the given tag and launch it
(2) Create an incognito window, bring up net-internals in one tab, switch to the "Capture" subtab
(3) In another tab, load http://cr.kungfoo.net/loading/1000spacers/  (believed relevance: Takes a while to load)
(4) Go back to the capture tab and click "Stop" repeatedly (doesn't respond very quickly)

What is the expected result?

The net-internals capture stops and the events source list is displayed.

What happens instead?

Chromium with the below stack backtrace.

Please use labels and text to provide additional information.


For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.

* thread #23: tid = 0x1ecba, 0x00000001161afa34 libbase.dylib`base::debug::BreakDebugger() + 20 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/debug/debugger_posix.cc:262, stop reason = EXC_BREAKPOINT (code=EXC_I386_BPT, subcode=0x0)
    frame #0: 0x00000001161afa34 libbase.dylib`base::debug::BreakDebugger() + 20 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/debug/debugger_posix.cc:262
    frame #1: 0x000000011624ace3 libbase.dylib`logging::LogMessage::~LogMessage() + 4387 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/logging.cc:759
    frame #2: 0x0000000116247715 libbase.dylib`logging::LogMessage::~LogMessage() + 21 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/logging.cc:533
    frame #3: 0x00000001163f7bfe libbase.dylib`base::internal::LockImpl::Lock() + 270 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/synchronization/lock_impl_posix.cc:65
    frame #4: 0x0000000116161033 libbase.dylib`base::Lock::Acquire() + 35 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/synchronization/lock.h:45
    frame #5: 0x0000000116161003 libbase.dylib`base::AutoLock::AutoLock(base::Lock&) + 35 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/synchronization/lock.h:115
    frame #6: 0x000000011616026d libbase.dylib`base::AutoLock::AutoLock(base::Lock&) + 29 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/synchronization/lock.h:114
    frame #7: 0x0000000116485854 libbase.dylib`base::ThreadCheckerImpl::CalledOnValidThread() const + 52 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/threading/thread_checker_impl.cc:19
    frame #8: 0x00000001094e5932 libchrome_dll.dylib`data_reduction_proxy::DataReductionProxyNetworkDelegate::SessionNetworkStatsInfoToValue() const + 114 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.cc:205
  * frame #9: 0x0000000109bca2d2 libchrome_dll.dylib`(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::OnGetSessionNetworkStats(base::ListValue const*) + 530 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../chrome/browser/ui/webui/net_internals/net_internals_ui.cc:885
    frame #10: 0x0000000109bd893a libchrome_dll.dylib`void base::internal::FunctorTraits<void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::*)(base::ListValue const*), void>::Invoke<scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl> const&, base::ListValue*>(void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::*)(base::ListValue const*), scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl> const&&&, base::ListValue*&&) + 154 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/bind_internal.h:214
    frame #11: 0x0000000109bd880f libchrome_dll.dylib`void base::internal::InvokeHelper<false, void>::MakeItSo<void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::* const&)(base::ListValue const*), scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl> const&, base::ListValue*>(void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::* const&&&)(base::ListValue const*), scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl> const&&&, base::ListValue*&&) + 95 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/bind_internal.h:285
    frame #12: 0x0000000109bd878c libchrome_dll.dylib`void base::internal::Invoker<base::internal::BindState<void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::*)(base::ListValue const*), scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl>, base::internal::OwnedWrapper<base::ListValue> >, void ()>::RunImpl<void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::* const&)(base::ListValue const*), std::__1::tuple<scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl>, base::internal::OwnedWrapper<base::ListValue> > const&, 0ul, 1ul>(void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::* const&&&)(base::ListValue const*), std::__1::tuple<scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl>, base::internal::OwnedWrapper<base::ListValue> > const&&&, base::IndexSequence<0ul, 1ul>) + 124 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/bind_internal.h:361
    frame #13: 0x0000000109bd869c libchrome_dll.dylib`base::internal::Invoker<base::internal::BindState<void ((anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl::*)(base::ListValue const*), scoped_refptr<(anonymous namespace)::NetInternalsMessageHandler::IOThreadImpl>, base::internal::OwnedWrapper<base::ListValue> >, void ()>::Run(base::internal::BindStateBase*) + 44 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/bind_internal.h:339
    frame #14: 0x00000001161b32fa libbase.dylib`base::internal::RunMixin<base::Callback<void (), (base::internal::CopyMode)0, (base::internal::RepeatMode)0> >::Run() + 90 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/callback.h:68
    frame #15: 0x00000001161b304b libbase.dylib`base::debug::TaskAnnotator::RunTask(char const*, base::PendingTask*) + 699 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/debug/task_annotator.cc:52
    frame #16: 0x00000001162a007b libbase.dylib`base::MessageLoop::RunTask(base::PendingTask*) + 923 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/message_loop/message_loop.cc:413
    frame #17: 0x00000001162a05f4 libbase.dylib`base::MessageLoop::DeferOrRunPendingTask(base::PendingTask) + 68 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/message_loop/message_loop.cc:422
    frame #18: 0x00000001162a102d libbase.dylib`base::MessageLoop::DoWork() + 669 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/message_loop/message_loop.cc:515
    frame #19: 0x00000001162b0f2f libbase.dylib`base::MessagePumpLibevent::Run(base::MessagePump::Delegate*) + 319 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/message_loop/message_pump_libevent.cc:218
    frame #20: 0x000000011629fb05 libbase.dylib`base::MessageLoop::RunHandler() + 645 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/message_loop/message_loop.cc:378
    frame #21: 0x0000000116382c73 libbase.dylib`base::RunLoop::Run() + 307 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/run_loop.cc:37
    frame #22: 0x0000000116482a0c libbase.dylib`base::Thread::Run(base::RunLoop*) + 428 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/threading/thread.cc:245
    frame #23: 0x000000011cc10e67 libcontent.dylib`content::BrowserThreadImpl::IOThreadRun(base::RunLoop*) + 71 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../content/browser/browser_thread_impl.cc:252
    frame #24: 0x000000011cc1116c libcontent.dylib`content::BrowserThreadImpl::Run(base::RunLoop*) + 588 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../content/browser/browser_thread_impl.cc:287
    frame #25: 0x0000000116483cd8 libbase.dylib`base::Thread::ThreadMain() + 3512 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/threading/thread.cc:328
    frame #26: 0x000000011645cf41 libbase.dylib`base::(anonymous namespace)::ThreadFunc(void*) + 705 at /Users/rdsmith/Sandboxen/chrome/src/out/Default/../../base/threading/platform_thread_posix.cc:71
    frame #27: 0x00007fff95dd199d libsystem_pthread.dylib`_pthread_body + 131
    frame #28: 0x00007fff95dd191a libsystem_pthread.dylib`_pthread_start + 168
    frame #29: 0x00007fff95dcf351 libsystem_pthread.dylib`thread_start + 13

Looking over the code, I think the problem is this line in NetInternalsMessageHandler::IOThreadImpl::OnGetSessionNetworkStats:

  if (http_network_session) {
    // TODO(mmenke):  This cast is ugly.  Can we get rid of it, or, better,
    // remove DRP data from net-internals entirely?
    data_reduction_proxy::DataReductionProxyNetworkDelegate* net_delegate =
        static_cast<data_reduction_proxy::DataReductionProxyNetworkDelegate*>(  // <<<<<
            context->network_delegate());
    if (net_delegate)
      network_info = net_delegate->SessionNetworkStatsInfoToValue();
  }

Comparing the instantiation of the URLRequestContextStorage in ProfileImplIOData and OffTheRecordProfileImplIOData, it appears that the first makes the delegate a DataReductionProxyNetworkDelegate (as assumed above) and the second does not.  So the above cast is not valid in incognito mode, and I think the lock error is compatible with calling a method on an invalid network delegate.

I don't know the context for the static cast, so I'm not sure whether this counts as a DRP bug or a NetLog bug, so I'll mention both components :-}.  I will note that I don't consider this a high priority bug (only showing up in a debugging context, with an easy workaround of running net-internals in the non-incognito window); I only pursued it this far to make sure it wasn't the CL I was working on.