Add flag for tab hover cards feature.

Bug: 910739
Change-Id: Ic708c771665e70979cf6011c482dd050ce749fe5
Reviewed-on: https://chromium-review.googlesource.com/c/1357539
Commit-Queue: Caroline Rising <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#613213}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 4faaa3b..ce375394 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1125,6 +1125,9 @@
 extern const char kSysInternalsName[];
 extern const char kSysInternalsDescription[];
 
+extern const char kTabHoverCardsName[];
+extern const char kTabHoverCardsDescription[];
+
 extern const char kTabsInCbdName[];
 extern const char kTabsInCbdDescription[];