Add flag to toggle external media format dialog

The enhanced format dialog for the file manager will be developed behind
a flag. This CL adds that flag, which will toggle between the old format
dialog and the new one.

Bug: 632988
Change-Id: Ifa7b436f1d7ee2130c57103c837b917fa0e29be8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1652761
Reviewed-by: Noel Gordon <[email protected]>
Reviewed-by: Luciano Pacheco <[email protected]>
Commit-Queue: Austin Tankiang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#667907}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index b4f8ad7d..87d7270 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1860,6 +1860,9 @@
 extern const char kFileManagerFeedbackPanelDescription[];
 extern const char kFileManagerFeedbackPanelName[];
 
+extern const char kFileManagerFormatDialogDescription[];
+extern const char kFileManagerFormatDialogName[];
+
 extern const char kFileManagerPiexWasmName[];
 extern const char kFileManagerPiexWasmDescription[];