Add infrastructure to run tests on android.

mojo/edk/system/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.
 
+if (is_android) {
+  import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
+}
+
 config("system_config") {
   defines = [
     # Ensures that dependent projects import the core functions on Windows.
     "MOJO_USE_SYSTEM_IMPL",
   ]
 }
 
 component("system") {
   output_name = "mojo_system_impl"
 
@@ skipping 121 matching lines @@
 
   deps = [
     ":system",
     "//base",
     "//base/test:test_support",
     "//mojo/edk/embedder:embedder_unittests",
     "//mojo/edk/test:test_support",
     "//testing/gtest",
   ]
 
+  if (is_android) {
+    deps += [
+      "//testing/android:native_test_native_code",
+    ]
+  }
+
   allow_circular_includes_from = [ "//mojo/edk/embedder:embedder_unittests" ]
 }
 
 # GYP version: mojo/edk/mojo_edk.gyp:mojo_message_pipe_perftests
 test("mojo_message_pipe_perftests") {
   sources = [
     "message_pipe_perftest.cc",
     "message_pipe_test_utils.h",
     "message_pipe_test_utils.cc",
     "test_utils.cc",
     "test_utils.h",
   ]
 
   deps = [
     ":system",
     "//base",
     "//base/test:test_support",
     "//base/test:test_support_perf",
     "//mojo/edk/test:test_support",
     "//testing/gtest",
   ]
 }
+
+if (is_android) {
+  unittest_apk("mojo_system_unittests_apk") {
+    deps = [
+      ":mojo_system_unittests",
+    ]
+    unittests_dep = ":mojo_system_unittests"
+  }
+}