Use an X event loop in the GPU process on Linux.

base/message_loop/message_pump_x11.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_X11_H
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_X11_H
 
 #include <bitset>
 #include <map>
 
@@ skipping 25 matching lines @@
  public:
   MessagePumpX11();
   virtual ~MessagePumpX11();
 
   // Returns default X Display.
   static Display* GetDefaultXDisplay();
 
   // Returns true if the system supports XINPUT2.
   static bool HasXInput2();
 
-#if !defined(TOOLKIT_GTK)
-  // Returns the UI message pump.
+  // Returns the UI or GPU message pump.
   static MessagePumpX11* Current();
-#endif
 
   // Adds/Removes |dispatcher| for the |xid|. This will route all messages from
   // the window |xid| to |dispatcher.
   void AddDispatcherForWindow(MessagePumpDispatcher* dispatcher,
                               unsigned long xid);
   void RemoveDispatcherForWindow(unsigned long xid);
 
   // Adds/Removes |dispatcher| to receive all events sent to the X root
   // window. A root window can have multiple dispatchers, and events on root
   // windows will be dispatched to all.
@@ skipping 67 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(MessagePumpX11);
 };
 
 #if !defined(TOOLKIT_GTK)
 typedef MessagePumpX11 MessagePumpForUI;
 #endif
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_X11_H