Remove include of Xlib.h in x11_atom_cache.h for the sake of tests

ui/gfx/x/x11_atom_cache.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 UI_GFX_X_X11_ATOM_CACHE_H_
 #define UI_GFX_X_X11_ATOM_CACHE_H_
 
+#include <map>
+#include <string>
+
 #include "base/basictypes.h"
 #include "ui/gfx/gfx_export.h"
 
-#include <map>
-#include <string>
-
-#include <X11/Xlib.h>
-
-// Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
-#undef RootWindow
+typedef unsigned long Atom;
+typedef struct _XDisplay XDisplay;
 
 namespace ui {
 
 // Pre-caches all Atoms on first use to minimize roundtrips to the X11
 // server. By default, GetAtom() will CHECK() that atoms accessed through
 // GetAtom() were passed to the constructor, but this behaviour can be changed
 // with allow_uncached_atoms().
 class GFX_EXPORT X11AtomCache {
  public:
   // Preinterns the NULL terminated list of string |to_cache_ on |xdisplay|.
-  X11AtomCache(Display* xdisplay, const char** to_cache);
+  X11AtomCache(XDisplay* xdisplay, const char** to_cache);
   ~X11AtomCache();
 
   // Returns the pre-interned Atom without having to go to the x server.
-  ::Atom GetAtom(const char*) const;
+  Atom GetAtom(const char*) const;
 
   // When an Atom isn't in the list of items we've cached, we should look it
   // up, cache it locally, and then return the result.
   void allow_uncached_atoms() { uncached_atoms_allowed_ = true; }
 
  private:
-  Display* xdisplay_;
+  XDisplay* xdisplay_;
 
   bool uncached_atoms_allowed_;
 
-  mutable std::map<std::string, ::Atom> cached_atoms_;
+  mutable std::map<std::string, Atom> cached_atoms_;
 
   DISALLOW_COPY_AND_ASSIGN(X11AtomCache);
 };
 
 }  // namespace ui
 
 #endif  // UI_GFX_X_X11_ATOM_CACHE_H_