Add FilesTrash flag

Add feature flag for adding Trash support in My files volume of FilesApp.

Bug: 953310
Change-Id: I3d06b39b77a744251a35001eb4c77bffab41383a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461508
Reviewed-by: Noel Gordon <[email protected]>
Commit-Queue: Joel Hockey <[email protected]>
Cr-Commit-Position: refs/heads/master@{#815410}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 92a5462..0dbcbc0c 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2389,6 +2389,9 @@
 extern const char kFilesTransferDetailsName[];
 extern const char kFilesTransferDetailsDescription[];
 
+extern const char kFilesTrashName[];
+extern const char kFilesTrashDescription[];
+
 extern const char kFilesZipMountName[];
 extern const char kFilesZipMountDescription[];