Cleanup GN BUILD files, gni's and imports.

mandoline/services/core_services/BUILD.gn

 # Copyright 2015 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.
 #
 # core_services should be thought of as a bundle of many of the services which
 # we ship with.
 
 import("//build/config/ui.gni")
-import("//third_party/mojo/src/mojo/public/mojo_application.gni")
-import("//testing/test.gni")
+import("//mojo/public/mojo_application.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 
   java_library_path = "$target_out_dir/java_library.dex.jar"
 
   mojo_android_application("core_services") {
     input_so = "$root_out_dir/lib.stripped/libcore_services.so"
     input_dex_jar = java_library_path
     deps = [
@@ skipping 54 matching lines @@
     "//mojo/services/tracing:lib",
   ]
 
   if (use_aura) {
     deps += [
       "//components/view_manager/public/cpp",
       "//mandoline/ui/omnibox:lib",
     ]
   }
 }