Linux: Fix Valgrind error in VisitedLinkEventsTest.Coalescense.

chrome/common/x11_util.cc

 // Copyright (c) 2009 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.
 
 // This file defines utility functions for X11 (Linux only). This code has been
 // ported from XCB since we can't use XCB on Ubuntu while its 32-bit support
 // remains woefully incomplete.
 
 #include "chrome/common/x11_util.h"
 
 #include <string.h>
 
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>
 #include <gtk/gtk.h>
 
 #include <sys/ipc.h>
 #include <sys/shm.h>
 
 #include <set>
 
 #include "base/logging.h"
 #include "base/gfx/size.h"
 #include "base/thread.h"
 #include "chrome/common/x11_util_internal.h"
 
 namespace x11_util {
 
+bool XDisplayExists() {
+  return (gdk_display_get_default() != NULL);
+}
+
 Display* GetXDisplay() {
   static Display* display = NULL;
 
   if (!display)
     display = gdk_x11_get_default_xdisplay();
 
   return display;
 }
 
 static bool DoQuerySharedMemorySupport(Display* dpy) {
@@ skipping 378 matching lines @@
     return false;
 
   if (children)
     XFree(children);
 
   *parent_is_root = root_window == *parent_window;
   return true;
 }
 
 }  // namespace x11_util