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

chrome/browser/media_galleries/fileapi/picasa_data_provider.cc

Index: chrome/browser/media_galleries/fileapi/picasa_data_provider.cc
diff --git a/chrome/browser/media_galleries/fileapi/picasa_data_provider.cc b/chrome/browser/media_galleries/fileapi/picasa_data_provider.cc
index 04360a930e6ce2e763f76a9ece40c96cc29373ce..15275cc21e8b50c52d84ef79728c8021aee6ce7a 100644
--- a/chrome/browser/media_galleries/fileapi/picasa_data_provider.cc
+++ b/chrome/browser/media_galleries/fileapi/picasa_data_provider.cc
@@ -51,7 +51,9 @@ PicasaDataProvider::PicasaDataProvider(const base::FilePath& database_path)
                  weak_factory_.GetWeakPtr()));
 }
 
-PicasaDataProvider::~PicasaDataProvider() {}
+PicasaDataProvider::~PicasaDataProvider() {
+  StopFilePathWatchOnMediaTaskRunner(std::move(temp_dir_watcher_));
+}
 
 void PicasaDataProvider::RefreshData(DataType needed_data,
                                      const ReadyCallback& ready_callback) {