Move ui::GetAtom to gfx::GetAtom

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/macros.h"
 #include "ui/gfx/gfx_export.h"
 #include "ui/gfx/x/x11_types.h"
 
 namespace base {
 template <typename T>
 struct DefaultSingletonTraits;
 }
 
-namespace ui {
+namespace gfx {
+
+// Gets the X atom for default display corresponding to atom_name.
+GFX_EXPORT XAtom GetAtom(const char* atom_name);
 
 // 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:
   static X11AtomCache* GetInstance();
 
-  // Returns the pre-interned Atom without having to go to the x server.
-  XAtom GetAtom(const char*) const;
-
  private:
+  friend XAtom GetAtom(const char* atom_name);
   friend struct base::DefaultSingletonTraits<X11AtomCache>;
 
   X11AtomCache();
   ~X11AtomCache();
 
+  // Returns the pre-interned Atom without having to go to the x server.
+  XAtom GetAtom(const char*) const;
+
   XDisplay* xdisplay_;
 
   mutable std::map<std::string, XAtom> cached_atoms_;
 
   DISALLOW_COPY_AND_ASSIGN(X11AtomCache);
 };
 
-}  // namespace ui
+}  // namespace gfx
 
 #endif  // UI_GFX_X_X11_ATOM_CACHE_H_