Move permission warning message handling from PermissionSet to PermissionMessageProvider.

chrome/common/extensions/permissions/permission_message_util.h

 // Copyright 2013 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_EXTENSIONS_PERMISSIONS_PERMISSION_MESSAGE_UTIL_H_
 #define CHROME_COMMON_EXTENSIONS_PERMISSIONS_PERMISSION_MESSAGE_UTIL_H_
 
 #include <set>
 #include <string>
 
 namespace extensions {
 class PermissionMessage;
+class PermissionSet;
+class URLPatternSet;
 }
 
 namespace permission_message_util {
 
 // Creates the corresponding permission message for a list of hosts.
 // The messages change depending on what hosts are present.
 extensions::PermissionMessage CreateFromHostList(
     const std::set<std::string>& hosts);
 
+std::set<std::string> GetDistinctHosts(
+    const extensions::URLPatternSet& host_patterns,
+    bool include_rcd,
+    bool exclude_file_scheme);
+
 }  // namespace permission_message_util
 
 #endif  // CHROME_COMMON_EXTENSIONS_PERMISSIONS_PERMISSION_MESSAGE_UTIL_H_