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

ui/gfx/x/x11_atom_cache.h

Index: ui/gfx/x/x11_atom_cache.h
diff --git a/ui/gfx/x/x11_atom_cache.h b/ui/gfx/x/x11_atom_cache.h
index fefa64205d06e404b75675cabe32b3f603f4e4bb..6a29df720c6fec9bd54f90b5c8d5e3daec287d30 100644
--- a/ui/gfx/x/x11_atom_cache.h
+++ b/ui/gfx/x/x11_atom_cache.h
@@ -5,16 +5,14 @@
 #ifndef UI_GFX_X_X11_ATOM_CACHE_H_
 #define UI_GFX_X_X11_ATOM_CACHE_H_
 
-#include "base/basictypes.h"
-#include "ui/gfx/gfx_export.h"
-
 #include <map>
 #include <string>
 
-#include <X11/Xlib.h>
+#include "base/basictypes.h"
+#include "ui/gfx/gfx_export.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 {
 
@@ -25,22 +23,22 @@ namespace ui {
 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);
 };