Add omnibox feature flag for context menu show full URLs

UX proposal: https://docs.google.com/document/d/19iu3ISlOw9L_PCpOh8LB4TSKC8uBPzSBiEnkZm4IiQI/edit#heading=h.qyrxas7ncbc9
Design doc: go/context-menu-unelide-dd

Bug: 1061576
Change-Id: I3627f0090112378f6df8bbaf274b40c35024a7c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2103291
Commit-Queue: Livvie Lin <[email protected]>
Reviewed-by: Tommy Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#751066}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 19a1f9a..338d96c 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -176,6 +176,9 @@
 extern const char kContextMenuSearchWithGoogleLensName[];
 extern const char kContextMenuSearchWithGoogleLensDescription[];
 
+extern const char kOmniboxContextMenuShowFullUrlsName[];
+extern const char kOmniboxContextMenuShowFullUrlsDescription[];
+
 extern const char kClickToOpenPDFName[];
 extern const char kClickToOpenPDFDescription[];