Omnibox: Add back kUIExperimentShowSuggestionFavicons flag

This is a partial revert of:
https://chromium-review.googlesource.com/c/chromium/src/+/1343366

It also no longer ties this flag to kExperimentalUi.

Bug: 931332, 900255
Change-Id: Idd1300a5ada1a76d48eb51fbc617cb7a7dc07069
Reviewed-on: https://chromium-review.googlesource.com/c/1467722
Commit-Queue: Tommy Li <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Cr-Commit-Position: refs/heads/master@{#631390}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index bb2c22b6..96d3194 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1429,6 +1429,12 @@
     "Changes the maximum number of autocomplete matches displayed in the "
     "Omnibox UI.";
 
+const char kOmniboxUIShowSuggestionFaviconsName[] =
+    "Omnibox UI Show Suggestion Favicons";
+const char kOmniboxUIShowSuggestionFaviconsDescription[] =
+    "Shows favicons instead of generic vector icons for URL suggestions in the "
+    "Omnibox dropdown.";
+
 const char kOmniboxUISwapTitleAndUrlName[] = "Omnibox UI Swap Title and URL";
 const char kOmniboxUISwapTitleAndUrlDescription[] =
     "In the omnibox dropdown, shows titles before URLs when both are "