Linux: Fix Valgrind error in VisitedLinkEventsTest.Coalescense.

chrome/common/x11_util.h

 // 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.
 
 #ifndef CHROME_COMMON_X11_UTIL_H_
 #define CHROME_COMMON_X11_UTIL_H_
 
 // This file declares utility functions for X11 (Linux only).
 //
 // These functions do not require the Xlib headers to be included (which is why
@@ skipping 16 matching lines @@
 class Size;
 }
 
 namespace x11_util {
 
 // These functions use the GDK default display and this /must/ be called from
 // the UI thread. Thus, they don't support multiple displays.
 
 // These functions cache their results.
 
+// Check if there's an open connection to an X server.
+bool XDisplayExists();
 // Return an X11 connection for the current, primary display.
 Display* GetXDisplay();
 // Return true iff the connection supports X shared memory
 bool QuerySharedMemorySupport(Display* dpy);
 // Return true iff the display supports Xrender
 bool QueryRenderSupport(Display* dpy);
 // Return the default screen number for the display
 int GetDefaultScreen(Display* display);
 
 // These functions do not cache their results
@@ skipping 62 matching lines @@
 
 // Find the immediate parent of an X window.
 //
 // parent_window: (output) the parent window of |window|, or 0.
 // parent_is_root: (output) true iff the parent of |window| is the root window.
 bool GetWindowParent(XID* parent_window, bool* parent_is_root, XID window);
 
 }  // namespace x11_util
 
 #endif  // CHROME_COMMON_X11_UTIL_H_