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

base/message_loop/message_pump_x11.cc

 // 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.
 
 #include "base/message_loop/message_pump_x11.h"
 
 #include <glib.h>
 #include <X11/X.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/XKBlib.h>
@@ skipping 140 matching lines @@
   if (!g_xdisplay)
     g_xdisplay = XOpenDisplay(NULL);
   return g_xdisplay;
 }
 
 // static
 bool MessagePumpX11::HasXInput2() {
   return InitializeXInput2();
 }
 
-#if !defined(TOOLKIT_GTK)
+#if defined(TOOLKIT_GTK)
+// static
+MessagePumpX11* MessagePumpX11::Current() {
+  MessageLoop* loop = MessageLoop::current();
+  return static_cast<MessagePumpX11*>(loop->pump_gpu());
+}
+#else
 // static
 MessagePumpX11* MessagePumpX11::Current() {
   MessageLoopForUI* loop = MessageLoopForUI::current();
   return static_cast<MessagePumpX11*>(loop->pump_ui());
 }
 #endif
 
 void MessagePumpX11::AddDispatcherForWindow(
     MessagePumpDispatcher* dispatcher,
     unsigned long xid) {
@@ skipping 136 matching lines @@
   if (FindEventTarget(xev) == x_root_window_) {
     FOR_EACH_OBSERVER(MessagePumpDispatcher, root_window_dispatchers_,
                       Dispatch(xev));
     return true;
   }
   MessagePumpDispatcher* dispatcher = GetDispatcherForXEvent(xev);
   return dispatcher ? dispatcher->Dispatch(xev) : true;
 }
 
 }  // namespace base