Update URLPatternSet to contain a std::set instead of std::vector.

chrome/common/extensions/extension.h

Index: chrome/common/extensions/extension.h
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index c1543da75029d57380877dec85a0bb0aab4f02cd..bde67078653f73b1602afcf9e7caa2a30163d1c5 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -544,22 +544,6 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   // sure the drive letter is uppercase.
   static FilePath MaybeNormalizePath(const FilePath& path);
 
-  // Returns the distinct hosts that can be displayed in the install UI or be
-  // used for privilege comparisons. This discards some of the detail that is
-  // present in the manifest to make it as easy as possible to process by users.
-  // In particular we disregard the scheme and path components of URLPatterns
-  // and de-dupe the result, which includes filtering out common hosts with
-  // differing RCDs. If |include_rcd| is true, then the de-duped result
-  // will be the first full entry, including its RCD. So if the list was
-  // "*.google.co.uk" and "*.google.com", the returned value would just be
-  // "*.google.co.uk". Keeping the RCD in the result is useful for display
-  // purposes when you want to show the user one sample hostname from the list.
-  // If you need to compare two URLPatternLists for security equality, then set
-  // |include_rcd| to false, which will return a result like "*.google.",
-  // regardless of the order of the patterns.
-  static std::vector<std::string> GetDistinctHosts(
-      const URLPatternList& host_patterns, bool include_rcd);
-
   // Returns true if this extension id is from a trusted provider.
   static bool IsTrustedId(const std::string& id);