mash: Exit the root process if the window manager service crashes

content/common/service_manager/service_manager_connection_impl.cc

Index: content/common/service_manager/service_manager_connection_impl.cc
diff --git a/content/common/service_manager/service_manager_connection_impl.cc b/content/common/service_manager/service_manager_connection_impl.cc
index 3e0008cbc9a6fac28a11ce2940547144152c45d6..4e511907808a5d42b03a251d4fc8bc4c876a9aeb 100644
--- a/content/common/service_manager/service_manager_connection_impl.cc
+++ b/content/common/service_manager/service_manager_connection_impl.cc
@@ -213,6 +213,9 @@ class ServiceManagerConnectionImpl::IOThreadContext
   void RemoveConnectionFilterOnIOThread(int filter_id) {
     base::AutoLock lock(lock_);
     auto it = connection_filters_.find(filter_id);
+    // TODO(crbug.com/687247): This DCHECK is hit when the browser is shut down
+    // by the service manager (e.g. in response to an ash crash under mash).
+    // Figure out why.
     DCHECK(it != connection_filters_.end());
     connection_filters_.erase(it);
   }