Add the request picker and a unit test

components/offline_pages/background/request_coordinator_unittest.cc

 // 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 "components/offline_pages/background/request_coordinator.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 154 matching lines @@
 
   // Check the request queue is as expected.
   EXPECT_EQ(1UL, last_requests().size());
   EXPECT_EQ(kUrl, last_requests()[0].url());
   EXPECT_EQ(kClientId, last_requests()[0].client_id());
 
   // Expect that the scheduler got notified.
   SchedulerStub* scheduler_stub = reinterpret_cast<SchedulerStub*>(
       coordinator()->GetSchedulerForTesting());
   EXPECT_TRUE(scheduler_stub->schedule_called());
-
-  // Check that the offliner callback got a response.
-  EXPECT_EQ(Offliner::RequestStatus::SAVED,
-            coordinator()->last_offlining_status());
-
-  // TODO(petewil): Expect that the scheduler got notified.
 }
 
 }  // namespace offline_pages