Next crash:

Received signal 11 SEGV_MAPERR 000000000000
#0 0x7f39506d9f6c base::debug::StackTrace::StackTrace()
#1 0x7f39506d9ae1 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#2 0x7f394d932530 <unknown>
#3 0x7f394f8f711a exo::WMHelperAsh::WMHelperAsh()
#4 0x7f395053cfce ChromeBrowserMainExtraPartsExo::PreProfileInit()
#5 0x7f395038aaea ChromeBrowserMainParts::PreProfileInit()
#6 0x7f395038ba5d ChromeBrowserMainPartsLinux::PreProfileInit()
#7 0x7f394f67512c chromeos::ChromeBrowserMainPartsChromeos::PreProfileInit()
#8 0x7f3950389d0c ChromeBrowserMainParts::PreMainMessageLoopRunImpl()
#9 0x7f39503895da ChromeBrowserMainParts::PreMainMessageLoopRun()
#10 0x7f394f674d6a chromeos::ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun()
#11 0x7f394efddfe0 content::BrowserMainLoop::PreMainMessageLoopRun()
#12 0x7f394f2d1537 content::StartupTaskRunner::RunAllTasksNow()
#13 0x7f394efdc0a1 content::BrowserMainLoop::CreateStartupTasks()
#14 0x7f394efe07e6 content::BrowserMainRunnerImpl::Initialize()
#15 0x7f394efd9644 content::BrowserMain()
#16 0x7f395034c196 content::ContentMainRunnerImpl::Run()
#17 0x7f39517584d2 service_manager::Main()
#18 0x7f395034b121 content::ContentMain()
#19 0x7f394eae1c60 ChromeMain

Peng, can you take this one? chrome --mus apparently doesn't create a views::MusClient. I don't know if that's intentional or not, and either way I'm not sure what to do with exo::WMHelper.

Sky, do you think now is a good time to chase on-device crashes, or should we wait for mushrome to be further along?

I'll post a CL to fix the issue in the original description.

FYI - views::MusClient creation is being skipped on --mus due to code below:

https://cs.chromium.org/chromium/src/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc?type=cs&sq=package:chromium&l=138

I would ignore trying to chase anything that is because of code trying to use ash/display classes. I'm hoping that will just work once we sort out 706589.

I suspect this code is crashing trying to use the cursor_manager, which doesn't work in mushrome mode. That's 631103. If it's the cursor_manager causing the crash an easy fix for now is a conditional. We'll need to fix it, but in the short term I suspect nothing bad would happen if the cursor observer isn't added.

It is intentional that --mus mode doesn't create MusClient.

Without looking too deeply I suspect exo should use WMHelperAsh in mushrome mode, most likely with a few early outs until we come classes (such as cursormanager) are made to work.

OK, since this isn't particularly exo-y I'll take a stab at it.

Peng, do you know if it's possible to exercise exo code on linux desktop, or only on device?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/205ee990e92962dbe5a0cceed476680c055c43b1

commit 205ee990e92962dbe5a0cceed476680c055c43b1
Author: jamescook <jamescook@chromium.org>
Date: Thu Apr 06 22:06:48 2017

chromeos: Fix chrome --mus startup crash on device

For now we need to use the fake IME for both --mus and --mash.

There's still another startup crash, but that will take a little more
work to fix.

BUG= 709097 
TEST=manual
TBR=zork@chromium.org

Review-Url: https://codereview.chromium.org/2801923003
Cr-Commit-Position: refs/heads/master@{#462641}

[modify] https://crrev.com/205ee990e92962dbe5a0cceed476680c055c43b1/chrome/browser/chromeos/input_method/input_method_manager_impl.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1af4615f37b6cd225efc2500c58ef4a8058cc945

commit 1af4615f37b6cd225efc2500c58ef4a8058cc945
Author: jamescook <jamescook@chromium.org>
Date: Fri Apr 07 00:00:06 2017

chromeos: Fix chrome --mus startup crashes on device

Skip things mushrome doesn't have yet:
* Cursor manager
* DeviceDataManager

Also fix some dbus service initialization.

After this CL we boot to the login screen. You can't log in yet because
input events are still broken.

BUG= 709097 
TEST=manual, chrome --mash and --mus start on desktop and on device

Review-Url: https://codereview.chromium.org/2801023004
Cr-Commit-Position: refs/heads/master@{#462694}

[modify] https://crrev.com/1af4615f37b6cd225efc2500c58ef4a8058cc945/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
[modify] https://crrev.com/1af4615f37b6cd225efc2500c58ef4a8058cc945/components/exo/wm_helper_ash.cc
[modify] https://crrev.com/1af4615f37b6cd225efc2500c58ef4a8058cc945/components/exo/wm_helper_mus.h