[remoting android] Add and build host code.

remoting/BUILD.gn

Index: remoting/BUILD.gn
diff --git a/remoting/BUILD.gn b/remoting/BUILD.gn
index 5415aa9609bf82ceae336427ec219e3f6e971b8d..72f1b6d485713fbdc446426c8f3b7d3c0b7f2f89 100644
--- a/remoting/BUILD.gn
+++ b/remoting/BUILD.gn
@@ -57,10 +57,13 @@ group("remoting_all") {
     deps += [
       "//remoting:remoting_perftests",
       "//remoting/host",
-      "//remoting/host:remoting_native_messaging_manifests",
     ]
 
-    if (!is_chromeos) {
+    if (!is_android) {
+      deps += [ "//remoting/host:remoting_native_messaging_manifests" ]
+    }
+
+    if (!is_chromeos && !is_android) {
       deps += [
         "//remoting/host:remoting_start_host",
         "//remoting/host/it2me:remote_assistance_host",