libassistant-v2: Add the feature to about flags

By adding the feature `LibAssistantV2` to the about flags, we could experiment this feature much easier.

Bug: b:258538951
Test: manual
Change-Id: Id86a8d08e4d74c95a46d1bd3e95403af3d028d95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4019813
Reviewed-by: Xiaohui Chen <[email protected]>
Commit-Queue: Tao Wu <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1069923}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index ca9ba25..68299fc 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -6161,6 +6161,10 @@
 const char kOobeMaterialNextDescription[] =
     "Feature to enable the Material Next design in out of box experience.";
 
+const char kLibAssistantV2MigrationName[] = "LibAssistant V2 migration";
+const char kLibAssistantV2MigrationDescription[] =
+    "Enables loading LibAssistant V2 for Assistant on ChromeOS.";
+
 // Prefer keeping this section sorted to adding new definitions down here.
 
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)