Add unit test for request coordiator

components/offline_pages/background/BUILD.gn

 # 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.
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 # GYP: //components/offline_pages/offline_pages.gypi:background_offliner
 static_library("background_offliner") {
@@ skipping 15 matching lines @@
     "//base",
     "//components/offline_pages:offline_pages",
     "//net",
     "//url",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
+    "request_coordinator_unittest.cc",
     "request_queue_in_memory_store_unittest.cc",
     "save_page_request_unittest.cc",
   ]
 
   deps = [
     ":background_offliner",
     "//base",
     "//base/test:test_support",
     "//components/offline_pages:offline_pages",
     "//testing/gtest",
     "//url",
   ]
 }