Create the BackgroundFetchBatchManager and initiate a download.

content/browser/background_fetch/background_fetch_batch_manager.cc

+// Copyright 2017 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 "content/browser/background_fetch/background_fetch_batch_manager.h"
+
+#include <string>
+#include <vector>
+
+#include "base/bind.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/download_manager.h"
+#include "content/public/browser/storage_partition.h"
+
+namespace content {
+
+BackgroundFetchBatchManager::BackgroundFetchBatchManager(
+    BrowserContext* browser_context,
+    StoragePartition* storage_partition)
+    : browser_context_(browser_context),
+      storage_partition_(storage_partition) {}
+
+BackgroundFetchBatchManager::~BackgroundFetchBatchManager() = default;
+
+void BackgroundFetchBatchManager::ProcessBatch(
+    const std::string& batch_uid,
+    const std::vector<FetchRequest>& requests) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  // Currently this only supports batches of size 1.

[Peter Beverloo, 2017/02/23 12:14:55]

TODO(crbug.com/123456). This is something that Anita will have to ensure in the
ServiceImpl.

[harkness, 2017/02/23 17:08:41]

Done.

+  DCHECK_EQ(1U, requests.size());
+  ProcessRequest(batch_uid, requests[0]);
+}
+
+void BackgroundFetchBatchManager::ProcessRequest(
+    const std::string& batch_uid,
+    const FetchRequest& fetch_request) {
+  // First add the new request to the internal map tracking in-progress
+  // requests.
+  fetch_map[batch_uid] = std::move(fetch_request);
+
+  // TODO(harkness): Check if the download is already in progress or completed.
+
+  // Send the fetch request to the DownloadManager.
+  std::unique_ptr<content::DownloadUrlParameters> params(

[Peter Beverloo, 2017/02/23 12:14:55]

nit: drop "content::". You are in that namespace.

[harkness, 2017/02/23 17:08:41]

Done.

+      new content::DownloadUrlParameters(

[Peter Beverloo, 2017/02/23 12:14:55]

nit:

base::MakeUnique<DownloadUrlParameters>(fetch_request.url(),
storage_partition_->GetURLRequestContext());

[harkness, 2017/02/23 17:08:41]

Done.

+          fetch_request.url(), storage_partition_->GetURLRequestContext()));
+  BrowserContext::GetDownloadManager(browser_context_)
+      ->DownloadUrl(std::move(params));
+}
+
+}  // namespace content