Implement rules removal for WebRequestRulesRegistry

chrome/browser/extensions/api/declarative/substring_set_matcher.cc

 // 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.
 
 #include "chrome/browser/extensions/api/declarative/substring_set_matcher.h"
 
 #include <queue>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 74 matching lines @@
       matches->insert(tree_[current_node].matches().begin(),
                       tree_[current_node].matches().end());
     } else {
       DCHECK_EQ(0, current_node);
     }
   }
 
   return old_number_of_matches != matches->size();
 }
 
+bool SubstringSetMatcher::IsEmpty() const {
+  // An empty tree consists of only the root node.
+  return patterns_.empty() && tree_.size() == 1u;
+}
+
 void SubstringSetMatcher::RebuildAhoCorasickTree() {
   tree_.clear();
 
   // Initialize root note of tree.
   AhoCorasickNode root;
   root.set_failure(0);
   tree_.push_back(root);
 
   // Insert all patterns.
   for (SubstringPatternSet::const_iterator i = patterns_.begin();
@@ skipping 105 matching lines @@
 void SubstringSetMatcher::AhoCorasickNode::AddMatch(SubstringPattern::ID id) {
   matches_.insert(id);
 }
 
 void SubstringSetMatcher::AhoCorasickNode::AddMatches(
     const SubstringSetMatcher::AhoCorasickNode::Matches& matches) {
   matches_.insert(matches.begin(), matches.end());
 }
 
 }  // namespace extensions