Always delete media galleries FilePathWatchers on the FILE thread.

chrome/browser/media_galleries/fileapi/iapps_data_provider.cc

 // Copyright 2013 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/media_galleries/fileapi/iapps_data_provider.h"
 
 #include <map>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/format_macros.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread_restrictions.h"
-#include "chrome/browser/media_galleries/fileapi/file_path_watcher_util.h"
 #include "chrome/browser/media_galleries/fileapi/media_file_system_backend.h"
 #include "chrome/common/media_galleries/itunes_library.h"
 #include "storage/browser/fileapi/native_file_util.h"
 #include "third_party/icu/source/common/unicode/locid.h"
 
 namespace iapps {
 
 IAppsDataProvider::IAppsDataProvider(const base::FilePath& library_path)
     : library_path_(library_path),
       needs_refresh_(true),
       is_valid_(false),
       weak_factory_(this) {
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
   DCHECK(!library_path_.empty());
 
   StartFilePathWatchOnMediaTaskRunner(
       library_path_,
       base::Bind(&IAppsDataProvider::OnLibraryWatchStarted,
                  weak_factory_.GetWeakPtr()),
       base::Bind(&IAppsDataProvider::OnLibraryChanged,
                  weak_factory_.GetWeakPtr()));
 }
 
-IAppsDataProvider::~IAppsDataProvider() {
-  StopFilePathWatchOnMediaTaskRunner(std::move(library_watcher_));
-}
+IAppsDataProvider::~IAppsDataProvider() {}
 
 bool IAppsDataProvider::valid() const {
   return is_valid_;
 }
 
 void IAppsDataProvider::set_valid(bool valid) {
   is_valid_ = valid;
 }
 
 void IAppsDataProvider::RefreshData(const ReadyCallback& ready_callback) {
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
   if (!needs_refresh_) {
     ready_callback.Run(valid());
     return;
   }
 
   // TODO(gbillock): this needs re-examination. Could be a refresh bug.
   needs_refresh_ = false;
   DoParseLibrary(library_path_, ready_callback);
 }
 
 const base::FilePath& IAppsDataProvider::library_path() const {
   return library_path_;
 }
 
 void IAppsDataProvider::OnLibraryWatchStarted(
-    std::unique_ptr<base::FilePathWatcher> library_watcher) {
+    MediaFilePathWatcherUniquePtr library_watcher) {
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
   library_watcher_ = std::move(library_watcher);
 }
 
 void IAppsDataProvider::OnLibraryChanged(const base::FilePath& path,
                                          bool error) {
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
   DCHECK_EQ(library_path_.value(), path.value());
   if (error)
     LOG(ERROR) << "Error watching " << library_path_.value();
   needs_refresh_ = true;
 }
 
 }  // namespace iapps