[remoting android] Add and build host code.

remoting/remoting_enable.gni

 # 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.
 
 # Keep in sync with remoting/remoting_enable.gypi.
 
 import("//build/config/ui.gni")
 
 enable_remoting_host = false
 enable_me2me_host = false
 
 # TODO(GYP) Make remoting hosts work on Mac.
 #if (is_mac) {
 #  enable_remoting_host = true
 #  enable_me2me_host = true
 #}
 
 if (is_win || (is_linux && !is_chromeos && use_x11)) {
   enable_remoting_host = true
   enable_me2me_host = true
 }
 
 if (is_linux && is_chromeos) {
   enable_remoting_host = true
 }
+
+if (is_android) {
+  enable_remoting_host = true
+}