Start refractoring extension permissions into ExtensionPermissionSet.

chrome/common/extensions/url_pattern_set.h

 // Copyright (c) 2011 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_URL_PATTERN_SET_H_
 #define CHROME_COMMON_EXTENSIONS_URL_PATTERN_SET_H_
 #pragma once
 
 #include <vector>
 
 #include "chrome/common/extensions/url_pattern.h"
 
 class GURL;
 
 // Represents the set of URLs an extension uses for web content.
 class URLPatternSet {
  public:
+  // Clears |out| and populates the set with the union of |set1| and |set2|.
+  // NOTE: this does not discard duplicates.
+  static void CreateUnion(const URLPatternSet& set1,
+                          const URLPatternSet& set2,
+                          URLPatternSet* out);
+
   URLPatternSet();
   URLPatternSet(const URLPatternSet& rhs);
   ~URLPatternSet();
   URLPatternSet& operator=(const URLPatternSet& rhs);
 
   bool is_empty() const;
 
   const URLPatternList& patterns() const { return patterns_; }
   void AddPattern(const URLPattern& pattern);
   void ClearPatterns();
 
   // Test if the extent contains a URL.
   bool MatchesURL(const GURL& url) const;
 
   // Returns true if there is a single URL that would be in two extents.
   bool OverlapsWith(const URLPatternSet& other) const;
 
  private:
   // The list of URL patterns that comprise the extent.
   URLPatternList patterns_;
 };
 
 #endif  // CHROME_COMMON_EXTENSIONS_URL_PATTERN_SET_H_