Cascade shutdown of instances

mash/browser_driver/browser_driver_application_delegate.cc

Index: mash/browser_driver/browser_driver_application_delegate.cc
diff --git a/mash/browser_driver/browser_driver_application_delegate.cc b/mash/browser_driver/browser_driver_application_delegate.cc
index 64ee8e4de7d7dbe05927247526514547f7c823a7..d30225ec8d1c58710c000c14fa23c7d7a4250a8d 100644
--- a/mash/browser_driver/browser_driver_application_delegate.cc
+++ b/mash/browser_driver/browser_driver_application_delegate.cc
@@ -7,6 +7,7 @@
 #include <stdint.h>
 
 #include "base/bind.h"
+#include "base/message_loop/message_loop.h"
 #include "components/mus/public/cpp/event_matcher.h"
 #include "mojo/shell/public/cpp/connection.h"
 #include "mojo/shell/public/cpp/connector.h"
@@ -42,11 +43,14 @@ void AssertTrue(bool success) {
   DCHECK(success);
 }
 
+void DoNothing() {}
+
 }  // namespace
 
 BrowserDriverApplicationDelegate::BrowserDriverApplicationDelegate()
     : connector_(nullptr),
-      binding_(this) {}
+      binding_(this),
+      weak_factory_(this) {}
 
 BrowserDriverApplicationDelegate::~BrowserDriverApplicationDelegate() {}
 
@@ -63,6 +67,12 @@ bool BrowserDriverApplicationDelegate::AcceptConnection(
   return true;
 }
 
+void BrowserDriverApplicationDelegate::ShellConnectionLost() {
+  // Prevent the code in AddAccelerators() from keeping this app alive.
+  binding_.set_connection_error_handler(base::Bind(&DoNothing));
+  base::MessageLoop::current()->QuitWhenIdle();
+}
+
 void BrowserDriverApplicationDelegate::OnAccelerator(
     uint32_t id, mus::mojom::EventPtr event) {
   switch (static_cast<Accelerator>(id)) {
@@ -92,7 +102,7 @@ void BrowserDriverApplicationDelegate::AddAccelerators() {
   // to re-add our accelerators when the window manager comes back up.
   binding_.set_connection_error_handler(
       base::Bind(&BrowserDriverApplicationDelegate::AddAccelerators,
-                 base::Unretained(this)));
+                 weak_factory_.GetWeakPtr()));
 
   for (const AcceleratorSpec& spec : g_spec) {
     registrar->AddAccelerator(