[subresource_filter] Replace KMP by std::search.

components/subresource_filter/core/common/flat/rules.fbs

 namespace subresource_filter.flat;
 
 // Corresponds to subresource_filter::proto::UrlPatternType.
 enum UrlPatternType : ubyte {
   SUBSTRING,
   WILDCARDED,
   REGEXP,
 }
 
 // Corresponds to subresource_filter::proto::AnchorType.
@@ skipping 35 matching lines @@
   anchor_left : AnchorType = NONE;
   anchor_right : AnchorType = NONE;
 
   // The list of domains to be included/excluded from the filter's affected set.
   // If a particular string in the list starts with '~' then the respective
   // domain is excluded, otherwise included.
   domains : [string];
 
   // A URL pattern in the format defined by |url_pattern_type|.
   url_pattern : string;
-
-  // The compound Knuth-Morris-Pratt failure function corresponding to
-  // |url_pattern|. Used for SUBSTRING and WILDCARDED URL patterns only.
-  //
-  // The |url_pattern| is split into subpatterns separated by a '*' wildcard.
-  // Then for each subpattern a failure function of the KMP algorithm is built,
-  // with the caveat that if some subpattern contains at least one '^'
-  // placeholder, all the separator characters in this subpattern are
-  // considered equivalent, and the failure function subarray is prefixed with
-  // the value 1.
-  //
-  // The failure functions of subpatterns are stored sequentially in the
-  // |failure_function| array. Some subpatterns, however, will not have a
-  // corresponding failure function, e.g. the first subpattern if the rule's
-  // |anchor_left| is BOUNDARY.
-  failure_function : [ubyte];
 }
 
 // Contains an N-gram (acting as a key in a hash table) and a list of URL rules
 // associated with that N-gram.
 table NGramToRules {
   // A string consisting of N (up to 8) non-special characters, which are stored
   // in the lowest N non-zero bytes, lower bytes corresponding to later symbols.
   ngram : ulong;
 
   // The list of rules containing |ngram| as a substring of their URL pattern.
@@ skipping 26 matching lines @@
 // The top-level data structure used to store URL rules.
 table IndexedRuleset {
   // The index of all blacklist URL rules.
   blacklist_index : UrlPatternIndex;
 
   // The index of all whitelist URL rules.
   whitelist_index : UrlPatternIndex;
 }
 
 root_type IndexedRuleset;