Fixing the issue of GDK discarding unsupported XInput events.

base/message_pump_glib_x.h

Index: base/message_pump_glib_x.h
diff --git a/base/message_pump_glib_x.h b/base/message_pump_glib_x.h
index 6bd29c9c53911925b203798aff65f20bc89a7c3e..fc0f405dcbc7d129101e92efc7e908be964e8c2d 100644
--- a/base/message_pump_glib_x.h
+++ b/base/message_pump_glib_x.h
@@ -31,8 +31,23 @@ class MessagePumpGlibX : public MessagePumpForUI {
   virtual bool RunOnce(GMainContext* context, bool block);
 
  private:
+  // Some XEvent's can't be directly read from X event queue and will go
+  // through GDK's dispatching process and may get discarded. Setting up
+  // the GdkEventFilter to intercept those XEvent's we are interested in
+  // and dispatch them so that they won't get lost.
+  static GdkFilterReturn GdkEventFilter(GdkXEvent* gxevent,
+                                        GdkEvent* gevent,
+                                        gpointer data);
+
   static void EventDispatcherX(GdkEvent* event, gpointer data);
 
+  // Decide whether we are interested in processing this XEvent.
+  bool ShouldCaptureXEvent(XEvent* event);
+
+  // Dispatching the XEvent and return true if we should exit the current loop
+  // of message processing.
+  bool ProcessXEvent(XEvent* event);
+
   // Sends the event to the observers. If an observer returns true, then it does
   // not send the event to any other observers and returns true. Returns false
   // if no observer returns true.