[Herb] Set up field trial for UI prototypes

ui/android/java/strings/android_ui_strings.grd

Index: ui/android/java/strings/android_ui_strings.grd
diff --git a/ui/android/java/strings/android_ui_strings.grd b/ui/android/java/strings/android_ui_strings.grd
index 1eee8497ffca8f35b827301882de466c0fa4f1fd..1ce51bc301dc5d1a6746535de7970aa02953eaf8 100644
--- a/ui/android/java/strings/android_ui_strings.grd
+++ b/ui/android/java/strings/android_ui_strings.grd
@@ -234,11 +234,6 @@
       <message name="IDS_AUTOFILL_KEYBOARD_ACCESSORY_CONTENT_DESCRIPTION" desc="The text announced by the screen reader when the autofill suggestions are shown.">
         Suggestions available
       </message>
-      
-      <!-- Herb strings -->
-      <message name="IDS_CACHE_NATIVE_FLAGS_REQUIRES_RESTART" desc="Toast telling the user that flags may not take effect until a restart." translateable="false">
-        Cached flags may not take effect until the browser is restarted again.
-      </message>
     </messages>
   </release>
 </grit>