Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

mojo/shell/public/cpp/lib/application_runner.cc

Index: mojo/shell/public/cpp/lib/application_runner.cc
diff --git a/mojo/shell/public/cpp/lib/application_runner.cc b/mojo/shell/public/cpp/lib/application_runner.cc
index 5253053d43f55ebe113404b038976858ab1abffc..31f3c74321cc30481c66ebf35775c9085e88c004 100644
--- a/mojo/shell/public/cpp/lib/application_runner.cc
+++ b/mojo/shell/public/cpp/lib/application_runner.cc
@@ -5,6 +5,7 @@
 #include "mojo/shell/public/cpp/application_runner.h"
 
 #include "base/at_exit.h"
+#include "base/bind.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ -13,6 +14,16 @@
 #include "mojo/shell/public/cpp/shell_connection.h"
 
 namespace mojo {
+namespace {
+
+void QuitMessageLoop() {
+  if (base::MessageLoop::current() &&
+      base::MessageLoop::current()->is_running()) {
+    base::MessageLoop::current()->QuitWhenIdle();

[sky, 2016/03/18 16:20:37]

If the messageloop is nested this quits the topmost runloop, which may not be
what you want. Instead create a RunLoop on 69 and call RunUntilIdle on it here.

+  }
+}
+
+}  // namespace
 
 int g_application_runner_argc;
 const char* const* g_application_runner_argv;
@@ -54,6 +65,7 @@ MojoResult ApplicationRunner::Run(MojoHandle shell_client_request_handle,
         client_.get(),
         MakeRequest<shell::mojom::ShellClient>(MakeScopedHandle(
             MessagePipeHandle(shell_client_request_handle)))));
+    connection_->set_connection_lost_closure(base::Bind(&QuitMessageLoop));
     loop->Run();
     // It's very common for the client to cache the app and terminate on errors.
     // If we don't delete the client before the app we run the risk of the