Add instrumentation hooks to mesaure which subresource filter rules are used.

components/subresource_filter/core/common/indexed_ruleset.h

 // Copyright 2016 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 COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_INDEXED_RULESET_H_
 #define COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_INDEXED_RULESET_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 64 matching lines @@
  public:
   // Returns whether the |buffer| of the given |size| contains a valid
   // flat::IndexedRuleset FlatBuffer.
   static bool Verify(const uint8_t* buffer, size_t size);
 
   // Creates an instance that matches URLs against the flat::IndexedRuleset
   // provided as the root object of serialized data in the |buffer| of the given
   // |size|.
   IndexedRulesetMatcher(const uint8_t* buffer, size_t size);
 
+  // Creates an instance that matches URLs against the flat::IndexedRuleset
+  // provided as the root object of serialized data in the |buffer| of the given
+  // |size|. Usage of rules will be recorded to |recorder|.
+  IndexedRulesetMatcher(const uint8_t* buffer,
+                        size_t size,
+                        std::unique_ptr<RuleRecorder> recorder);
+
   // Returns whether the subset of subresource filtering rules specified by the
   // |activation_type| should be disabled for the |document| loaded from
   // |parent_document_origin|. Always returns false if |activation_type| ==
   // ACTIVATION_TYPE_UNSPECIFIED or the |document_url| is not valid. Unlike
   // page-level activation, such rules can be used to have fine-grained control
   // over the activation of filtering within (sub-)documents.
   bool ShouldDisableFilteringForDocument(
       const GURL& document_url,
       const url::Origin& parent_document_origin,
       proto::ActivationType activation_type) const;
 
   // Returns whether the network request to |url| of |element_type| initiated by
   // |document_origin| is not allowed to proceed. Always returns false if the
   // |url| is not valid or |element_type| == ELEMENT_TYPE_UNSPECIFIED.
   bool ShouldDisallowResourceLoad(const GURL& url,
                                   const FirstPartyOrigin& first_party,
                                   proto::ElementType element_type,
                                   bool disable_generic_rules) const;
 
  private:
   const flat::IndexedRuleset* root_;
 
   UrlPatternIndexMatcher blacklist_;
   UrlPatternIndexMatcher whitelist_;
   UrlPatternIndexMatcher deactivation_;
 
+  std::unique_ptr<RuleRecorder> recorder_;
+
   DISALLOW_COPY_AND_ASSIGN(IndexedRulesetMatcher);
 };
 
 }  // namespace subresource_filter
 
 #endif  // COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_INDEXED_RULESET_H_