Add high-precision timing histograms.

components/subresource_filter/core/common/BUILD.gn

Index: components/subresource_filter/core/common/BUILD.gn
diff --git a/components/subresource_filter/core/common/BUILD.gn b/components/subresource_filter/core/common/BUILD.gn
index b48b5550311dbed8e194ee64ee9a2d79d3b5b772..ddb3916c97db5812c9e778eef7f39fb05370eecc 100644
--- a/components/subresource_filter/core/common/BUILD.gn
+++ b/components/subresource_filter/core/common/BUILD.gn
@@ -21,6 +21,7 @@ static_library("common") {
     "memory_mapped_ruleset.cc",
     "memory_mapped_ruleset.h",
     "ngram_extractor.h",
+    "scoped_timers.h",
     "string_splitter.h",
     "uint64_hasher.h",
     "unindexed_ruleset.cc",
@@ -67,6 +68,7 @@ source_set("unit_tests") {
     "indexed_ruleset_unittest.cc",
     "knuth_morris_pratt_unittest.cc",
     "ngram_extractor_unittest.cc",
+    "scoped_timers_unittest.cc",
     "string_splitter_unittest.cc",
     "unindexed_ruleset_unittest.cc",
     "url_pattern_matching_unittest.cc",
@@ -74,6 +76,7 @@ source_set("unit_tests") {
   deps = [
     ":common",
     "//base",
+    "//base/test:test_support",
     "//testing/gtest",
     "//third_party/protobuf:protobuf_lite",
     "//url",