Fix some TODO(GYP) in the GN build.

sync/tools/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("//testing/test.gni")
 
-if (is_linux && !is_chromeos) {
-  # TODO(GYP): Figure out which of these work and are needed on other platforms.
+# These are used by developers so don't compile on mobile OS's.
+if (!is_ios && !is_android && !is_chromecast) {

[brettw, 2016/05/23 22:06:26]

This matches the condition in src/BUILD.gn.

   source_set("common") {
     testonly = true
 
     sources = [
       "null_invalidation_state_tracker.cc",
       "null_invalidation_state_tracker.h",
     ]
 
     deps = [
       "//base",
@@ skipping 36 matching lines @@
       "//components/invalidation/impl",
       "//components/sync_driver",
       "//jingle:notifier",
       "//net",
       "//net:test_support",
       "//sync",
       "//sync:test_support_sync_core",
     ]
   }
 }