x11: Move X event handling out of the message-pump.

ui/wm/core/wm_state.cc

Index: ui/wm/core/wm_state.cc
diff --git a/ui/wm/core/wm_state.cc b/ui/wm/core/wm_state.cc
index afb84c7c92fa17b735fc255b102d3ccbeee15d03..991940e7323711075ecac5ef98d7d6280dab004d 100644
--- a/ui/wm/core/wm_state.cc
+++ b/ui/wm/core/wm_state.cc
@@ -4,6 +4,7 @@
 
 #include "ui/wm/core/wm_state.h"
 
+#include "ui/events/platform/platform_event_source.h"
 #include "ui/wm/core/transient_window_controller.h"
 #include "ui/wm/core/transient_window_stacking_client.h"
 
@@ -14,6 +15,8 @@ WMState::WMState()
       transient_window_client_(new TransientWindowController) {
   aura::client::SetWindowStackingClient(window_stacking_client_.get());
   aura::client::SetTransientWindowClient(transient_window_client_.get());
+  if (!ui::PlatformEventSource::GetInstance())
+    event_source_ = ui::PlatformEventSource::CreateDefault();
 }
 
 WMState::~WMState() {