Revert 212948 "Made MessagePump a non-thread safe class."

trunk/src/base/message_loop/message_pump_gtk.h

Index: trunk/src/base/message_loop/message_pump_gtk.h
===================================================================
--- trunk/src/base/message_loop/message_pump_gtk.h	(revision 212951)
+++ trunk/src/base/message_loop/message_pump_gtk.h	(working copy)
@@ -43,7 +43,6 @@
 class BASE_EXPORT MessagePumpGtk : public MessagePumpGlib {
  public:
   MessagePumpGtk();
-  virtual ~MessagePumpGtk();
 
   // Dispatch an available GdkEvent. Essentially this allows a subclass to do
   // some task before/after calling the default handler (EventDispatcher).
@@ -52,6 +51,9 @@
   // Returns default X Display.
   static Display* GetDefaultXDisplay();
 
+ protected:
+  virtual ~MessagePumpGtk();
+
  private:
   // Invoked from EventDispatcher. Notifies all observers we're about to
   // process an event.