Clean up //services/BUILD.gn.

R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/1122343002
diff --git a/services/BUILD.gn b/services/BUILD.gn
index d0a487b..84876b8 100644
--- a/services/BUILD.gn
+++ b/services/BUILD.gn
@@ -2,9 +2,6 @@
 # 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")
-import("//mojo/public/mojo.gni")
-
 group("services") {
   deps = [
     "//services/clipboard",