Fix missing #include build error from r251504.

TBR=vandebo@chromium.org

Review URL: https://codereview.chromium.org/167423003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251512 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/media_galleries/media_folder_finder.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/task_runner_util.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/media_galleries/fileapi/media_path_filter.h"
 #include "chrome/browser/storage_monitor/storage_monitor.h"
 #include "content/public/browser/browser_thread.h"