Require FilePathWatcher destructor to be called in sequence with Watch().

chrome/browser/media_galleries/fileapi/picasa_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/picasa_data_provider.h"
 
 #include <utility>
 
 #include "base/bind_helpers.h"
 #include "base/callback.h"
@@ skipping 33 matching lines @@
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
 
   StartFilePathWatchOnMediaTaskRunner(
       database_path_.DirName().AppendASCII(kPicasaTempDirName),
       base::Bind(&PicasaDataProvider::OnTempDirWatchStarted,
                  weak_factory_.GetWeakPtr()),
       base::Bind(&PicasaDataProvider::OnTempDirChanged,
                  weak_factory_.GetWeakPtr()));
 }
 
-PicasaDataProvider::~PicasaDataProvider() {}
+PicasaDataProvider::~PicasaDataProvider() {
+  StopFilePathWatchOnMediaTaskRunner(std::move(temp_dir_watcher_));
+}
 
 void PicasaDataProvider::RefreshData(DataType needed_data,
                                      const ReadyCallback& ready_callback) {
   MediaFileSystemBackend::AssertCurrentlyOnMediaSequence();
   // TODO(tommycli): Need to watch the database_path_ folder and handle
   // rereading the data when it changes.
 
   if (state_ == INVALID_DATA_STATE) {
     ready_callback.Run(false /* success */);
     return;
@@ skipping 193 matching lines @@
     if (total_counts[name] != 1) {
       name = base::StringPrintf("%s (%d)", name.c_str(),
                                 ++current_counts[name]);
     }
 
     result_map->insert(std::pair<std::string, AlbumInfo>(name, info_list[i]));
   }
 }
 
 }  // namespace picasa