Add an API to Pause and Resume background offlining requests.

components/offline_pages/background/request_queue_in_memory_store.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_queue_in_memory_store.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/offline_pages/background/save_page_request.h"
@@ skipping 38 matching lines @@
     } else {
       result = RequestQueue::UpdateRequestResult::REQUEST_DOES_NOT_EXIST;
     }
     results.push_back(std::make_pair(request_id, result));
   }
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                 base::Bind(callback, results));
 }
 
+void RequestQueueInMemoryStore::ChangeRequestsState(
+    const std::vector<int64_t>& request_ids,
+    const SavePageRequest::RequestState new_state,
+    const UpdateCallback& callback) {
+  int count = 0;
+
+  for (int64_t request_id : request_ids) {
+    auto pair = requests_.find(request_id);
+    if (pair != requests_.end()) {
+      ++count;
+      pair->second.set_request_state(new_state);
+    }
+  }
+
+  RequestQueueStore::UpdateStatus status =
+      count > 0 ? UpdateStatus::UPDATED : UpdateStatus::FAILED;
+
+  base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
+                                                base::Bind(callback, status));
+}
+
 void RequestQueueInMemoryStore::Reset(const ResetCallback& callback) {
   requests_.clear();
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                 base::Bind(callback, true));
 }
 
 }  // namespace offline_pages