Revert of Merge duplicate code in invalidation helper.

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.
   source_set("common") {
     testonly = true
 
     sources = [
+      "invalidation_helper.cc",
+      "invalidation_helper.h",
       "null_invalidation_state_tracker.cc",
       "null_invalidation_state_tracker.h",
     ]
 
     deps = [
       "//base",
       "//components/invalidation/impl",
       "//sync",
     ]
   }
@@ skipping 29 matching lines @@
       "//base",
       "//components/invalidation/impl",
       "//jingle:notifier",
       "//net",
       "//net:test_support",
       "//sync",
       "//sync:test_support_sync_core",
     ]
   }
 }