[remoting android] Add and build host code.

remoting/host/pairing_registry_delegate_android.cc

Index: remoting/host/pairing_registry_delegate_android.cc
diff --git a/remoting/host/pairing_registry_delegate_mac.cc b/remoting/host/pairing_registry_delegate_android.cc
similarity index 78%
copy from remoting/host/pairing_registry_delegate_mac.cc
copy to remoting/host/pairing_registry_delegate_android.cc
index 9d3ae4438caea30de26efcf853a7d34d34d74bab..ce5e774ef88031b321a8902c3039db8e8bf76c88 100644
--- a/remoting/host/pairing_registry_delegate_mac.cc
+++ b/remoting/host/pairing_registry_delegate_android.cc
@@ -1,11 +1,9 @@
-// Copyright 2013 The Chromium Authors. All rights reserved.
+// Copyright 2016 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.
 
 #include "remoting/host/pairing_registry_delegate.h"
 
-#include "base/task_runner.h"
-
 namespace remoting {
 
 using protocol::PairingRegistry;