Simplify //mojo/public/c/system targets

examples/device_name/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/android/rules.gni")
 import("//mojo/public/mojo_application.gni")
 
 shared_library("libdevice_name") {
   output_name = "device_name"
 
   deps = [
     "//base",
-    "//mojo/public/c/system:for_shared_library",
+    "//mojo/public/c/system",
     "//mojo/public/cpp/application:standalone",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/utility",
+    "//mojo/public/platform/native:system",
     ":jni_headers",
   ]
 
   sources = [
     "device_name.cc",
   ]
 }
 
 generate_jni("jni_headers") {
   sources = [
@@ skipping 11 matching lines @@
     "//base:base_java",
   ]
 
   dex_path = dex_output_path
 }
 
 mojo_android_application("device_name") {
   input_so = "$root_out_dir/lib.stripped/libdevice_name.so"
   input_dex_jar = dex_output_path
 }