Use TaskScheduler instead of blocking pool in arc_downloads_watcher_service.cc.

chrome/browser/chromeos/arc/downloads_watcher/arc_downloads_watcher_service.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 "chrome/browser/chromeos/arc/downloads_watcher/arc_downloads_watcher_service.h"
 
 #include <string.h>
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <memory>
 #include <utility>
 
 #include "base/callback.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/time/time.h"
 #include "chrome/browser/download/download_prefs.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/chrome_paths.h"
 #include "components/arc/arc_bridge_service.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
 
 // Mapping from Android file paths to last modified timestamps.
@@ skipping 238 matching lines @@
                    weak_ptr_factory_.GetWeakPtr()),
         kBuildTimestampMapDelay);
   } else {
     last_notify_time_ = base::TimeTicks::Now();
   }
 }
 
 void ArcDownloadsWatcherService::DownloadsWatcher::DelayBuildTimestampMap() {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
   DCHECK(outstanding_task_);
-  base::PostTaskAndReplyWithResult(
-      BrowserThread::GetBlockingPool(), FROM_HERE,
+  base::PostTaskWithTraitsAndReplyWithResult(
+      FROM_HERE, base::TaskTraits().MayBlock(),
       base::Bind(&BuildTimestampMapCallback, downloads_dir_),
       base::Bind(&DownloadsWatcher::OnBuildTimestampMap,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void ArcDownloadsWatcherService::DownloadsWatcher::OnBuildTimestampMap(
     std::pair<base::TimeTicks, TimestampMap> timestamp_and_map) {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
   DCHECK(outstanding_task_);
   base::TimeTicks snapshot_time = timestamp_and_map.first;
   TimestampMap current_timestamp_map = std::move(timestamp_and_map.second);
   std::vector<base::FilePath> changed_paths =
       CollectChangedPaths(last_timestamp_map_, current_timestamp_map);
 
   last_timestamp_map_ = std::move(current_timestamp_map);
 
   std::vector<std::string> string_paths(changed_paths.size());
   for (size_t i = 0; i < changed_paths.size(); ++i) {
     string_paths[i] = changed_paths[i].value();
   }
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(callback_, base::Passed(std::move(string_paths))));
-  if (last_notify_time_ > snapshot_time) {
-    base::PostTaskAndReplyWithResult(
-        BrowserThread::GetBlockingPool(), FROM_HERE,
-        base::Bind(&BuildTimestampMapCallback, downloads_dir_),
-        base::Bind(&DownloadsWatcher::OnBuildTimestampMap,
-                   weak_ptr_factory_.GetWeakPtr()));
-  } else {
+  if (last_notify_time_ > snapshot_time)
+    DelayBuildTimestampMap();
+  else
     outstanding_task_ = false;
-  }
 }
 
 ArcDownloadsWatcherService::ArcDownloadsWatcherService(
     ArcBridgeService* bridge_service)
     : ArcService(bridge_service), weak_ptr_factory_(this) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   arc_bridge_service()->file_system()->AddObserver(this);
 }
 
 ArcDownloadsWatcherService::~ArcDownloadsWatcherService() {
@@ skipping 38 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   auto* instance = ARC_GET_INSTANCE_FOR_METHOD(
       arc_bridge_service()->file_system(), RequestMediaScan);
   if (!instance)
     return;
   instance->RequestMediaScan(paths);
 }
 
 }  // namespace arc