Add initial components unit tests to GN build.

components/autocomplete/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.
 
 static_library("autocomplete") {
   sources = [
     "autocomplete_input.cc",
     "autocomplete_input.h",
     "autocomplete_scheme_classifier.h",
     "url_prefix.cc",
     "url_prefix.h",
   ]
 
   deps = [
     "//base",
     "//components/metrics/proto",
     "//components/url_fixer",
     "//net",
     "//url",
   ]
+
+  forward_dependent_configs_from = [
+    "//components/metrics/proto",
+  ]
 }
 
 static_library("test_support") {
   sources = [
     "test_scheme_classifier.cc",
     "test_scheme_classifier.h",
   ]
 
   deps = [
     ":autocomplete",
     "//base",
     "//components/metrics/proto",
   ]
 }
+
+source_set("unit_tests") {
+  sources = [
+    "autocomplete_input_unittest.cc",
+  ]
+
+  deps = [
+    ":autocomplete",
+    ":test_support",
+    "//testing/gtest",
+  ]
+}