Reland: "Tab Search: Add chrome://flags entry for Tab Search"

This addition is necessary to allow users to disable the feature once
the experiment is enabled.

Reland comment: Original CL was missing metadata.

Bug: 1099917
Change-Id: I89b92c0c0b2ec2065fff4598976c9536b0b19a8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341382
Reviewed-by: Robert Liao <[email protected]>
Commit-Queue: Thomas Lukaszewicz <[email protected]>
Cr-Commit-Position: refs/heads/master@{#795607}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index ebc9b4ac..8acb781 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -564,6 +564,11 @@
 extern const char kEnableSyncTrustedVaultName[];
 extern const char kEnableSyncTrustedVaultDescription[];
 
+#if BUILDFLAG(ENABLE_TAB_SEARCH)
+extern const char kEnableTabSearchName[];
+extern const char kEnableTabSearchDescription[];
+#endif  // BUILDFLAG(ENABLE_TAB_SEARCH)
+
 extern const char kEnableTextFragmentAnchorName[];
 extern const char kEnableTextFragmentAnchorDescription[];