GN: Add mojo_shell_tests, get more things working on android

mojo/services/public/cpp/input_events/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("//mojo/system.gni")
+
 component("input_events") {
   deps = [
     "//base",
     "//ui/events",
     "//ui/gfx/geometry",
     "//mojo/environment:chromium",
     "//mojo/services/public/interfaces/input_events",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/cpp/geometry",
   ]
+  deps += mojo_system_for_component
 
   defines = [
     "MOJO_INPUT_EVENTS_IMPLEMENTATION",
   ]
 
   sources = [
     "lib/input_events_type_converters.cc",
     "input_events_type_converters.h",
     "mojo_input_events_export.h",
   ]
-
-  if (is_component_build) {
-    deps += [ "//mojo/system" ]
-  }
 }