Move root_window_host* in aura to window_tree_host*.

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[email protected]
BUG=

Review URL: https://codereview.chromium.org/160573002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251379 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ui/aura/window_tree_host.h b/ui/aura/window_tree_host.h
index c6fd3086..cc5e8b3a 100644
--- a/ui/aura/window_tree_host.h
+++ b/ui/aura/window_tree_host.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef UI_AURA_ROOT_WINDOW_HOST_H_
-#define UI_AURA_ROOT_WINDOW_HOST_H_
+#ifndef UI_AURA_WINDOW_TREE_HOST_H_
+#define UI_AURA_WINDOW_TREE_HOST_H_
 
 #include <vector>
 
@@ -173,4 +173,4 @@
 
 }  // namespace aura
 
-#endif  // UI_AURA_ROOT_WINDOW_HOST_H_
+#endif  // UI_AURA_WINDOW_TREE_HOST_H_