Add high-precision timing histograms.

components/subresource_filter/core/browser/ruleset_service.cc

Index: components/subresource_filter/core/browser/ruleset_service.cc
diff --git a/components/subresource_filter/core/browser/ruleset_service.cc b/components/subresource_filter/core/browser/ruleset_service.cc
index c35c51f43de566808d4ea04c98b0819655089fc3..09f3bb866f8dbe9b06575dc5835aaf31bd6b839d 100644
--- a/components/subresource_filter/core/browser/ruleset_service.cc
+++ b/components/subresource_filter/core/browser/ruleset_service.cc
@@ -27,6 +27,7 @@
 #include "components/subresource_filter/core/common/copying_file_stream.h"
 #include "components/subresource_filter/core/common/indexed_ruleset.h"
 #include "components/subresource_filter/core/common/proto/rules.pb.h"
+#include "components/subresource_filter/core/common/scoped_uma_histogram_timers.h"
 #include "components/subresource_filter/core/common/unindexed_ruleset.h"
 #include "third_party/protobuf/src/google/protobuf/io/zero_copy_stream_impl_lite.h"
 
@@ -279,6 +280,8 @@ IndexedRulesetVersion RulesetService::IndexAndWriteRuleset(
 bool RulesetService::IndexRuleset(base::File unindexed_ruleset_file,
                                   RulesetIndexer* indexer) {
   SCOPED_UMA_HISTOGRAM_TIMER("SubresourceFilter.IndexRuleset.WallDuration");
+  SCOPED_UMA_HISTOGRAM_THREAD_TIMER(
+      "SubresourceFilter.IndexRuleset.CPUDuration");
 
   int64_t unindexed_ruleset_size = unindexed_ruleset_file.GetLength();
   CopyingFileInputStream copying_stream(std::move(unindexed_ruleset_file));