Add more components tests to GN build.

components/query_parser/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source_set("query_parser") {
   sources = [
     "query_parser.cc",
     "query_parser.h",
     "snippet.cc",
     "snippet.h",
   ]
 
   deps = [
     "//base",
     "//base:i18n",
     "//third_party/icu",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "query_parser_unittest.cc",
+    "snippet_unittest.cc",
+  ]
+  deps = [
+    ":query_parser",
+    "//testing/gtest",
+  ]
+}