Integrate CriticalPersistedTabData behind a flag

CriticalPersistedTabData is a redesign/replacement of TabState
and has been integrated behind a flag.

Being a redesign/replacement of TabState, this has increased the
binary size. When TabState is deprecated it is expected the binary
size will reduce by a similar amount.

Binary-Size: Increase is temporary.
Bug: 1114312
Change-Id: I01053eed2ca2179b86f436a2685660fd422399c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359371
Commit-Queue: David Maunder <[email protected]>
Reviewed-by: Tommy Nyquist <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Cr-Commit-Position: refs/heads/master@{#800269}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 50610b4..e35a503 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1554,6 +1554,9 @@
 extern const char kCloseTabSuggestionsName[];
 extern const char kCloseTabSuggestionsDescription[];
 
+extern const char kCriticalPersistedTabDataName[];
+extern const char kCriticalPersistedTabDataDescription[];
+
 extern const char kContentIndexingDownloadHomeName[];
 extern const char kContentIndexingDownloadHomeDescription[];