Implement correct logic for URLPatternSet set operators.

extensions/common/url_pattern_set.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 EXTENSIONS_COMMMON_URL_PATTERN_SET_H_
 #define EXTENSIONS_COMMMON_URL_PATTERN_SET_H_
 
 #include <set>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 41 matching lines @@
 
   URLPatternSet& operator=(const URLPatternSet& rhs);
   bool operator==(const URLPatternSet& rhs) const;
 
   bool is_empty() const;
   size_t size() const;
   const std::set<URLPattern>& patterns() const { return patterns_; }
   const_iterator begin() const { return patterns_.begin(); }
   const_iterator end() const { return patterns_.end(); }
 
-  // Adds a pattern to the set. Returns true if a new pattern was inserted,
-  // false if the pattern was already in the set.
+  // Adds a pattern to the set. If a more general pattern is added, the more
+  // specific ones are removed from the set. Returns true if a new pattern was
+  // inserted, false if the pattern was already in the set.
   bool AddPattern(const URLPattern& pattern);
 
   // Adds all patterns from |set| into this.
   void AddPatterns(const URLPatternSet& set);
 
   void ClearPatterns();
 
   // Returns true if every URL that matches |set| is matched by this. In other
   // words, if every pattern in |set| is encompassed by a pattern in this.
   bool Contains(const URLPatternSet& set) const;
@@ skipping 15 matching lines @@
                 int valid_schemes,
                 bool allow_file_access,
                 std::string* error);
 
   bool Populate(const std::vector<std::string>& patterns,
                 int valid_schemes,
                 bool allow_file_access,
                 std::string* error);
 
  private:
+  // Directly inserts a pattern in the set without checking for more
+  // generic/more specific containment conditions.
+  bool InsertPattern(const URLPattern& pattern);
+
   // The list of URL patterns that comprise the extent.
   std::set<URLPattern> patterns_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMMON_URL_PATTERN_SET_H_