Sync more GN unit tests with GYP.

components/search_engines/BUILD.gn

Index: components/search_engines/BUILD.gn
diff --git a/components/search_engines/BUILD.gn b/components/search_engines/BUILD.gn
index c5aeec92dc99711a969ccba3e0282ad01678fe61..4c555bdbdc86569f23203a1222b6319aa58757b1 100644
--- a/components/search_engines/BUILD.gn
+++ b/components/search_engines/BUILD.gn
@@ -86,12 +86,31 @@ source_set("test_support") {
     "testing_search_terms_data.h",
   ]
 
-  deps = [
+  public_deps = [
     ":search_engines",
     "//testing/gtest",
   ]
 }
 
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "default_search_manager_unittest.cc",
+    "default_search_policy_handler_unittest.cc",
+    "default_search_pref_migration_unittest.cc",
+    "keyword_table_unittest.cc",
+    "search_host_to_urls_map_unittest.cc",
+    "template_url_prepopulate_data_unittest.cc",
+    "template_url_service_util_unittest.cc",
+    "template_url_unittest.cc",
+  ]
+  deps = [
+    ":test_support",
+    "//testing/gmock",
+    "//testing/gtest",
+  ]
+}
+
 json_to_struct("prepopulated_engines") {
   visibility = [ ":*" ]