Add user_prefs and visitedlink components to GN build.

components/visitedlink/common/BUILD.gn

Index: components/visitedlink/common/BUILD.gn
diff --git a/components/visitedlink/common/BUILD.gn b/components/visitedlink/common/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..61d3ef221035b4ed57c14102f63ea5071996e094
--- /dev/null
+++ b/components/visitedlink/common/BUILD.gn
@@ -0,0 +1,21 @@
+# 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("common") {
+  output_name = "visitedlink_common"
+  sources = [
+    "visitedlink_common.cc",
+    "visitedlink_common.h",
+    "visitedlink_message_generator.cc",
+    "visitedlink_message_generator.h",
+    "visitedlink_messages.h",
+  ]
+
+  deps = [
+    "//base",
+    "//content/public/common",
+    "//ipc",
+    "//url"
+  ]
+}