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

components/subresource_filter/core/common/indexed_ruleset.h

Index: components/subresource_filter/core/common/indexed_ruleset.h
diff --git a/components/subresource_filter/core/common/indexed_ruleset.h b/components/subresource_filter/core/common/indexed_ruleset.h
index 00588f8a0a76514dd8699da5e167fb5ff4c1a881..aea8712c64febe7ac6486a951fac80f3a0a900e4 100644
--- a/components/subresource_filter/core/common/indexed_ruleset.h
+++ b/components/subresource_filter/core/common/indexed_ruleset.h
@@ -82,6 +82,13 @@ class IndexedRulesetMatcher {
   // |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| ==
@@ -108,6 +115,8 @@ class IndexedRulesetMatcher {
   UrlPatternIndexMatcher whitelist_;
   UrlPatternIndexMatcher deactivation_;
 
+  std::unique_ptr<RuleRecorder> recorder_;
+
   DISALLOW_COPY_AND_ASSIGN(IndexedRulesetMatcher);
 };