Introduce feature flag crostini-use-dlc

This flag will control whether Chrome sources the termina VM from
component updater or DLC.

Bug: 953544
Change-Id: I4bc61e61cf56127a50ef215b422acc5958573e63
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2328569
Commit-Queue: Fergus Dall <[email protected]>
Reviewed-by: David Munro <[email protected]>
Reviewed-by: Nicholas Verne <[email protected]>
Cr-Commit-Position: refs/heads/master@{#794019}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index b8c8c59..f6c6a00 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2050,6 +2050,9 @@
 extern const char kCrostiniWebUIUpgraderName[];
 extern const char kCrostiniWebUIUpgraderDescription[];
 
+extern const char kCrostiniUseDlcName[];
+extern const char kCrostiniUseDlcDescription[];
+
 extern const char kCryptAuthV2DeviceActivityStatusName[];
 extern const char kCryptAuthV2DeviceActivityStatusDescription[];