[TTS] Add aggregation of CTR metrics to the CS component.

components/contextual_search/BUILD.gn

Index: components/contextual_search/BUILD.gn
diff --git a/components/contextual_search/BUILD.gn b/components/contextual_search/BUILD.gn
index ab2af0280c5246099746b78b47e4fb1c554bec5d..2de0face5d36b1b5c503bca2883020108cc41e76 100644
--- a/components/contextual_search/BUILD.gn
+++ b/components/contextual_search/BUILD.gn
@@ -19,6 +19,9 @@ static_library("browser") {
   sources = [
     "browser/contextual_search_js_api_service_impl.cc",
     "browser/contextual_search_js_api_service_impl.h",
+    "browser/ctr_aggregator.cc",
+    "browser/ctr_aggregator.h",
+    "browser/device_int_storage.h",
   ]
   deps = [
     ":mojo_bindings",
@@ -26,6 +29,18 @@ static_library("browser") {
   ]
 }
 
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "browser/ctr_aggregator_unittest.cc",
+  ]
+
+  deps = [
+    ":browser",
+    "//testing/gtest",
+  ]
+}
+
 # GYP version: components/contextual_search.gypi:contextual_search_renderer
 static_library("renderer") {
   sources = [