[MerchantTrust] Add configurations for page info and IPH

This CL contains the following:
* Add configurations for the "Store info" row in page info and its
related IPH.
* Add flags for the "Store info" row in page info.
* Update flag expirations for Merchant Viewer.

Bug: 1255136
Change-Id: I8ba7bcecf73f64e14cdc71a5b38328fa1b119c02
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3209488
Auto-Submit: Zhiyuan Cai <[email protected]>
Commit-Queue: Zhiyuan Cai <[email protected]>
Reviewed-by: Ayman Almadhoun <[email protected]>
Cr-Commit-Position: refs/heads/main@{#929232}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index b838f745..2189a37 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3317,6 +3317,10 @@
     "Enable a history sub page to the page info menu, and a button to forget "
     "a site, removing all preferences and history.";
 
+const char kPageInfoStoreInfoName[] = "Page info store info";
+const char kPageInfoStoreInfoDescription[] =
+    "Enable a store info row to the page info menu on eligible pages.";
+
 extern const char kPageInfoV2DesktopName[];
 extern const char kPageInfoV2DesktopDescription[];