This gets mojo_launcher.so a little further along toward running.

mojo/services/native_viewport/native_viewport_x11.cc

Index: mojo/services/native_viewport/native_viewport_x11.cc
diff --git a/mojo/services/native_viewport/native_viewport_x11.cc b/mojo/services/native_viewport/native_viewport_x11.cc
index be7d1cd79442637531c07ce0942a4aeb18db4df5..50397b87d23ecabdc329254940b4e65e7a61da33 100644
--- a/mojo/services/native_viewport/native_viewport_x11.cc
+++ b/mojo/services/native_viewport/native_viewport_x11.cc
@@ -53,8 +53,9 @@ class NativeViewportX11 : public NativeViewport,
     atom_wm_delete_window_ = XInternAtom(display, "WM_DELETE_WINDOW", 1);
     XSetWMProtocols(display, window_, &atom_wm_delete_window_, 1);
 
-    // Assumes there is only one instance per process.
-    event_source_ = ui::PlatformEventSource::CreateDefault();
+    event_source_.reset(ui::PlatformEventSource::GetInstance());
+    if (!event_source_.get())
+      event_source_ = ui::PlatformEventSource::CreateDefault();
     ui::PlatformEventSource::GetInstance()->AddPlatformEventDispatcher(this);
 
     delegate_->OnAcceleratedWidgetAvailable(window_);