Add more components tests to the GN build.

components/bookmarks/browser/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.
 
 import("//build/config/ui.gni")
 
 source_set("browser") {
   sources = [
     "base_bookmark_model_observer.cc",
     "base_bookmark_model_observer.h",
@@ skipping 41 matching lines @@
     "//ui/gfx",
     "//url",
   ]
 
   if (toolkit_views) {
     sources += [
       "bookmark_node_data_views.cc",
     ]
   }
 }
+
+source_set("unit_tests") {
+  sources = [
+    "bookmark_codec_unittest.cc",
+    "bookmark_expanded_state_tracker_unittest.cc",
+    "bookmark_index_unittest.cc",
+    "bookmark_model_unittest.cc",
+    "bookmark_utils_unittest.cc",
+  ]
+
+  deps = [
+    ":browser",
+    "//testing/gtest",
+  ]
+}